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Ray S, Stampf JL, Kudlacek O, Yang JW, Schicker KW, Graf Y, Losgott T, Boehm S, Salzer I. A triple cysteine motif as major determinant of the modulation of neuronal K V7 channels by the paracetamol metabolite N-acetyl-p-benzo quinone imine. Br J Pharmacol 2024. [PMID: 38657956 DOI: 10.1111/bph.16380] [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: 10/20/2023] [Revised: 02/19/2024] [Accepted: 03/10/2024] [Indexed: 04/26/2024] Open
Abstract
BACKGROUND AND PURPOSE The analgesic action of paracetamol involves KV7 channels, and its metabolite N-acetyl-p-benzo quinone imine (NAPQI), a cysteine modifying reagent, was shown to increase currents through such channels in nociceptors. Modification of cysteine residues by N-ethylmaleimide, H2O2, or nitric oxide has been found to modulate currents through KV7 channels. The study aims to identify whether, and if so which, cysteine residues in neuronal KV7 channels might be responsible for the effects of NAPQI. EXPERIMENTAL APPROACH To address this question, we used a combination of perforated patch-clamp recordings, site-directed mutagenesis, and mass spectrometry applied to recombinant KV7.1 to KV7.5 channels. KEY RESULTS Currents through the cardiac subtype KV7.1 were reduced by NAPQI. Currents through all other subtypes were increased, either by an isolated shift of the channel voltage dependence to more negative values (KV7.3) or by such a shift combined with increased maximal current levels (KV7.2, KV7.4, KV7.5). A stretch of three cysteine residues in the S2-S3 linker region of KV7.2 was necessary and sufficient to mediate these effects. CONCLUSION AND IMPLICATION The paracetamol metabolite N-acetyl-p-benzo quinone imine (NAPQI) modifies cysteine residues of KV7 subunits and reinforces channel gating in homomeric and heteromeric KV7.2 to KV7.5, but not in KV7.1 channels. In KV7.2, a triple cysteine motif located within the S2-S3 linker region mediates this reinforcement that can be expected to reduce the excitability of nociceptors and to mediate antinociceptive actions of paracetamol.
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Affiliation(s)
- Sutirtha Ray
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Jan-Luca Stampf
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Oliver Kudlacek
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Jae-Won Yang
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Klaus W Schicker
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Yvonne Graf
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Thomas Losgott
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Stefan Boehm
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Isabella Salzer
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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Alberto-Silva AS, Hemmer S, Bock HA, Alves da Silva L, Scott KR, Kastner N, Bhatt M, Niello M, Jäntsch K, Kudlacek O, Bossi E, Stockner T, Meyer MR, McCorvy JD, Brandt SD, Kavanagh P, Sitte HH. Bioisosteric analogs of MDMA with improved pharmacological profile. bioRxiv 2024:2024.04.08.588083. [PMID: 38645142 PMCID: PMC11030374 DOI: 10.1101/2024.04.08.588083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
3,4-Methylenedioxymethamphetamine (MDMA, ' ecstasy' ) is re-emerging in clinical settings as a candidate for the treatment of specific psychiatric disorders (e.g. post-traumatic stress disorder) in combination with psychotherapy. MDMA is a psychoactive drug, typically regarded as an empathogen or entactogen, which leads to transporter-mediated monoamine release. Despite its therapeutic potential, MDMA can induce dose-, individual-, and context-dependent untoward effects outside safe settings. In this study, we investigated whether three new methylenedioxy bioisosteres of MDMA improve its off-target profile. In vitro methods included radiotracer assays, transporter electrophysiology, bioluminescence resonance energy transfer and fluorescence-based assays, pooled human liver microsome/S9 fraction incubation with isozyme mapping, and liquid chromatography coupled to high-resolution mass spectrometry. In silico methods included molecular docking. Compared with MDMA, all three MDMA bioisosteres (ODMA, TDMA, and SeDMA) showed similar pharmacological activity at human serotonin and dopamine transporters (hSERT and hDAT, respectively) but decreased activity at 5-HT 2A/2B/2C receptors. Regarding their hepatic metabolism, they differed from MDMA, with N -demethylation being the only metabolic route shared, and without forming phase II metabolites. Additional screening for their interaction with human organic cation transporters (hOCTs) and plasma membrane transporter (hPMAT) revealed a weaker interaction of the MDMA analogs with hOCT1, hOCT2, and hPMAT. Our findings suggest that these new MDMA analogs might constitute appealing therapeutic alternatives to MDMA, sparing the primary pharmacological activity at hSERT and hDAT, but displaying a reduced activity at 5-HT 2A/2B/2C receptors and reduced hepatic metabolism. Whether these MDMA bioisosteres may pose lower risk alternatives to the clinically re-emerging MDMA warrants further studies.
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Ün D, Kovalchuk V, El-Kasaby A, Kasture A, Koban F, Kudlacek O, Freissmuth M, Sucic S. Breaking the rules of SLC6 transporters: Export of the human creatine transporter-1 from the endoplasmic reticulum is supported by its N-terminus. J Neurochem 2024. [PMID: 38419374 DOI: 10.1111/jnc.16088] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 02/13/2024] [Accepted: 02/15/2024] [Indexed: 03/02/2024]
Abstract
Mutations in the human creatine transporter 1 (CRT1/SLC6A8) cause the creatine transporter deficiency syndrome, which is characterized by intellectual disability, epilepsy, autism, and developmental delay. The vast majority of mutations cause protein misfolding and hence reduce cell surface expression. Hence, it is important to understand the molecular machinery supporting folding and export of CRT1 from the endoplasmic reticulum (ER). All other SLC6 members thus far investigated rely on a C-terminal motif for binding the COPII-component SEC24 to drive their ER export; their N-termini are dispensable. Here, we show that, in contrast, in CRT1 the C-terminal ER-export motif is cryptic and it is the N-terminus, which supports ER export. This conclusion is based on the following observations: (i) siRNA-induced depletion of individual SEC24 isoforms revealed that CRT1 relied on SEC24C for ER export. However, mutations of the C-terminal canonical ER-export motif of CRT1 did not impair its cell surface delivery. (ii) Nevertheless, the C-terminal motif of CRT1 was operational in a chimeric protein comprising the serotonin transporter (SERT/SLC6A4) and the C-terminus of CRT1. (iii) Tagging of the N-terminus-but not the C-terminus-with yellow fluorescent protein (YFP) resulted in ER retention. (iv) Serial truncations of the N-terminus showed that removal of ≥51 residues of CRT1 impaired surface delivery, because the truncated CRT1 were confined to the ER. (v) Mutation of P51 to alanine also reduced cell surface delivery of CRT1 and relieved its dependence on SEC24C. Thus, the ER-export motif in the N-terminus of CRT1 overrides the canonical C-terminal motif.
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Affiliation(s)
- Didem Ün
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Vasylyna Kovalchuk
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Ali El-Kasaby
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Ameya Kasture
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | - Florian Koban
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Oliver Kudlacek
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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4
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Mayer FP, Niello M, Bulling S, Zhang YW, Li Y, Kudlacek O, Holy M, Kooti F, Sandtner W, Rudnick G, Schmid D, Sitte HH. Mephedrone induces partial release at human dopamine transporters but full release at human serotonin transporters. Neuropharmacology 2023; 240:109704. [PMID: 37703919 DOI: 10.1016/j.neuropharm.2023.109704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 07/07/2023] [Accepted: 08/31/2023] [Indexed: 09/15/2023]
Abstract
Mephedrone (4-methylmethcathinone) is a cathinone derivative that is recreationally consumed for its energizing and empathogenic effects. The stimulating properties are believed to arise from the ability of mephedrone to interact with the high-affinity transporters for dopamine (DA) (DAT) and norepinephrine (NET), whereas the entactogenic effect presumably relies on its activity at the serotonin (5-HT) transporter (SERT). Early studies found that mephedrone acts as a releaser at NET, DAT and SERT, and thus promotes efflux of the respective monoamines. Evidence linked drug-induced reverse transport of 5-HT via SERT to prosocial effects, whereas activity at DAT is strongly correlated with abuse liability. Consequently, we sought to evaluate the pharmacology of mephedrone at human (h) DAT and SERT, heterologously expressed in human embryonic kidney 293 cells, in further detail. In line with previous studies, we report that mephedrone evokes carrier-mediated release via hDAT and hSERT. We found this effect to be sensitive to the protein kinase C inhibitor GF109203X. Electrophysiological recordings revealed that mephedrone is actively transported by hDAT and hSERT. However, mephedrone acts as a full substrate of hSERT but as a partial substrate of hDAT. Furthermore, when compared to fully efficacious releasing agents at hDAT and hSERT (i.e. S(+)-amphetamine and para-chloroamphetamine, respectively) mephedrone displays greater efficacy as a releaser at hSERT than at hDAT. In summary, this study provides additional insights into the molecular mechanism of action of mephedrone at hDAT and hSERT.
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Affiliation(s)
- Felix P Mayer
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, A-1090, Vienna, Austria
| | - Marco Niello
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, A-1090, Vienna, Austria
| | - Simon Bulling
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, A-1090, Vienna, Austria
| | - Yuan-Wei Zhang
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06520-8066, USA
| | - Yang Li
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, A-1090, Vienna, Austria
| | - Oliver Kudlacek
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, A-1090, Vienna, Austria
| | - Marion Holy
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, A-1090, Vienna, Austria
| | - Fatemeh Kooti
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, A-1090, Vienna, Austria
| | - Walter Sandtner
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, A-1090, Vienna, Austria
| | - Gary Rudnick
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06520-8066, USA
| | - Diethart Schmid
- Institute for Physiology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, A-1090, Vienna, Austria
| | - Harald H Sitte
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, A-1090, Vienna, Austria; Hourani Center for Applied Scientific Research, Al-Ahliyya Amman University, Amman, Jordan; Center for Addiction Research and Science - AddRess, Medical University of Vienna, Waehringer Strasse 13a, A-1090, Vienna, Austria.
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5
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Mayer FP, Niello M, Cintulova D, Sideromenos S, Maier J, Li Y, Bulling S, Kudlacek O, Schicker K, Iwamoto H, Deng F, Wan J, Holy M, Katamish R, Sandtner W, Li Y, Pollak DD, Blakely RD, Mihovilovic MD, Baumann MH, Sitte HH. Serotonin-releasing agents with reduced off-target effects. Mol Psychiatry 2023; 28:722-732. [PMID: 36352123 PMCID: PMC9645344 DOI: 10.1038/s41380-022-01843-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 10/06/2022] [Accepted: 10/12/2022] [Indexed: 11/10/2022]
Abstract
Increasing extracellular levels of serotonin (5-HT) in the brain ameliorates symptoms of depression and anxiety-related disorders, e.g., social phobias and post-traumatic stress disorder. Recent evidence from preclinical and clinical studies established the therapeutic potential of drugs inducing the release of 5-HT via the 5-HT-transporter. Nevertheless, current 5-HT releasing compounds under clinical investigation carry the risk for abuse and deleterious side effects. Here, we demonstrate that S-enantiomers of certain ring-substituted cathinones show preference for the release of 5-HT ex vivo and in vivo, and exert 5-HT-associated effects in preclinical behavioral models. Importantly, the lead cathinone compounds (1) do not induce substantial dopamine release and (2) display reduced off-target activity at vesicular monoamine transporters and 5-HT2B-receptors, indicative of low abuse-liability and low potential for adverse events. Taken together, our findings identify these agents as lead compounds that may prove useful for the treatment of disorders where elevation of 5-HT has proven beneficial.
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Affiliation(s)
- Felix P. Mayer
- grid.22937.3d0000 0000 9259 8492Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, 1090 Vienna, Austria ,grid.255951.fDepartment of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL 33458 USA
| | - Marco Niello
- grid.22937.3d0000 0000 9259 8492Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, 1090 Vienna, Austria
| | - Daniela Cintulova
- grid.5329.d0000 0001 2348 4034Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria
| | - Spyridon Sideromenos
- grid.22937.3d0000 0000 9259 8492Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | - Julian Maier
- grid.22937.3d0000 0000 9259 8492Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, 1090 Vienna, Austria
| | - Yang Li
- grid.22937.3d0000 0000 9259 8492Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, 1090 Vienna, Austria ,grid.8547.e0000 0001 0125 2443Present Address: Institutes of Brain Science, Fudan University, Shanghai, 200032 China
| | - Simon Bulling
- grid.22937.3d0000 0000 9259 8492Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, 1090 Vienna, Austria
| | - Oliver Kudlacek
- grid.22937.3d0000 0000 9259 8492Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, 1090 Vienna, Austria
| | - Klaus Schicker
- grid.22937.3d0000 0000 9259 8492Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, 1090 Vienna, Austria
| | - Hideki Iwamoto
- grid.255951.fStiles-Nicholson Brain Institute and Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL 33458 USA
| | - Fei Deng
- grid.11135.370000 0001 2256 9319IDG McGovern Institute for Brain Research, Peking University, 100871 Beijing, China
| | - Jinxia Wan
- grid.11135.370000 0001 2256 9319IDG McGovern Institute for Brain Research, Peking University, 100871 Beijing, China
| | - Marion Holy
- grid.22937.3d0000 0000 9259 8492Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, 1090 Vienna, Austria
| | - Rania Katamish
- grid.255951.fDepartment of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL 33458 USA
| | - Walter Sandtner
- grid.22937.3d0000 0000 9259 8492Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, 1090 Vienna, Austria
| | - Yulong Li
- grid.11135.370000 0001 2256 9319IDG McGovern Institute for Brain Research, Peking University, 100871 Beijing, China
| | - Daniela D. Pollak
- grid.22937.3d0000 0000 9259 8492Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | - Randy D. Blakely
- grid.255951.fDepartment of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL 33458 USA ,grid.255951.fStiles-Nicholson Brain Institute and Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL 33458 USA
| | - Marko D. Mihovilovic
- grid.5329.d0000 0001 2348 4034Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria
| | - Michael H. Baumann
- grid.94365.3d0000 0001 2297 5165Designer Drug Research Unit, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224 USA
| | - Harald H. Sitte
- grid.22937.3d0000 0000 9259 8492Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Waehringer Strasse 13a, 1090 Vienna, Austria ,grid.22937.3d0000 0000 9259 8492AddRess, Center for Addiction Research and Science, Medical University of Vienna, Vienna, Austria
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Luethi D, Maier J, Rudin D, Szöllősi D, Angenoorth TJF, Stankovic S, Schittmayer M, Burger I, Yang JW, Jaentsch K, Holy M, Das AK, Brameshuber M, Camacho-Hernandez GA, Casiraghi A, Newman AH, Kudlacek O, Birner-Gruenberger R, Stockner T, Schütz GJ, Sitte HH. Phosphatidylinositol 4,5-bisphosphate (PIP 2) facilitates norepinephrine transporter dimerization and modulates substrate efflux. Commun Biol 2022; 5:1259. [PMID: 36396757 PMCID: PMC9672106 DOI: 10.1038/s42003-022-04210-1] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 11/01/2022] [Indexed: 11/19/2022] Open
Abstract
The plasmalemmal norepinephrine transporter (NET) regulates cardiovascular sympathetic activity by clearing extracellular norepinephrine in the synaptic cleft. Here, we investigate the subunit stoichiometry and function of NET using single-molecule fluorescence microscopy and flux assays. In particular, we show the effect of phosphatidylinositol 4,5-bisphosphate (PIP2) on NET oligomerization and efflux. NET forms monomers (~60%) and dimers (~40%) at the plasma membrane. PIP2 depletion results in a decrease in the average oligomeric state and decreases NET-mediated substrate efflux while not affecting substrate uptake. Mutation of the putative PIP2 binding residues R121, K334, and R440 to alanines does not affect NET dimerization but results in decreased substrate efflux that is not altered upon PIP2 depletion; this indicates that PIP2 interactions with these residues affect NET-mediated efflux. A dysregulation of norepinephrine and PIP2 signaling have both been implicated in neuropsychiatric and cardiovascular diseases. This study provides evidence that PIP2 directly regulates NET organization and function.
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Affiliation(s)
- Dino Luethi
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
- Institute of Applied Physics, TU Wien, Lehargasse 6, 1060, Vienna, Austria
| | - Julian Maier
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Deborah Rudin
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Dániel Szöllősi
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Thomas J F Angenoorth
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Stevan Stankovic
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Matthias Schittmayer
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9, 1060, Vienna, Austria
| | - Isabella Burger
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9, 1060, Vienna, Austria
| | - Jae-Won Yang
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Kathrin Jaentsch
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Marion Holy
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Anand Kant Das
- Institute of Applied Physics, TU Wien, Lehargasse 6, 1060, Vienna, Austria
- Physics Program, New York University Abu Dhabi, Saadiyat Island, 129188, Abu Dhabi, United Arab Emirates
| | - Mario Brameshuber
- Institute of Applied Physics, TU Wien, Lehargasse 6, 1060, Vienna, Austria
| | - Gisela Andrea Camacho-Hernandez
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse - Intramural Research Program, Baltimore, MD, 21224, USA
| | - Andrea Casiraghi
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse - Intramural Research Program, Baltimore, MD, 21224, USA
- Department of Pharmaceutical Sciences, University of Milan, Via Luigi Mangiagalli 25, 20133, Milan, Italy
| | - Amy Hauck Newman
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse - Intramural Research Program, Baltimore, MD, 21224, USA
| | - Oliver Kudlacek
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Ruth Birner-Gruenberger
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9, 1060, Vienna, Austria
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010, Graz, Austria
| | - Thomas Stockner
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria
| | - Gerhard J Schütz
- Institute of Applied Physics, TU Wien, Lehargasse 6, 1060, Vienna, Austria.
| | - Harald H Sitte
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090, Vienna, Austria.
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Lang PT, Ploeckl B, Fischer R, Griener M, Kircher M, Kudlacek O, Phillips G, Sieglin B, Yamamoto S, Treutterer W, Team AUG. Actuator Development Step by Step: Pellet Particle Flux Control for Single- and Multiple-Source Systems. Fusion Science and Technology 2022. [DOI: 10.1080/15361055.2021.1940034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- P. T. Lang
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - B. Ploeckl
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - R. Fischer
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - M. Griener
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - M. Kircher
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - O. Kudlacek
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - G. Phillips
- Fusion for Energy-F4E, Boltzmannstr. 2, 85748 Garching, Germany
| | - B. Sieglin
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - S. Yamamoto
- National Institutes for Quantum and Radiological Technology, Naka Fusion Institute, 801-1 Mukoyama, Naka-shi, Ibaraki-ken, Japan 311-0193
| | - W. Treutterer
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
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Saha K, Yang JW, Hofmaier T, Venkatesan S, Steinkellner T, Kudlacek O, Sucic S, Freissmuth M, Sitte HH. Constitutive Endocytosis of the Neuronal Glutamate Transporter Excitatory Amino Acid Transporter-3 Requires ARFGAP1. Front Physiol 2021; 12:671034. [PMID: 34040545 PMCID: PMC8141794 DOI: 10.3389/fphys.2021.671034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 02/22/2021] [Accepted: 04/13/2021] [Indexed: 12/12/2022] Open
Abstract
The eukaryotic endocytic pathway regulates protein levels available at the plasma membrane by recycling them into specific endosomal compartments. ARFGAP1 is a component of the coat protein I (COPI) complex but it also plays a role in promoting adapter protein-2 (AP-2) mediated endocytosis. The excitatory amino acid transporter-3 (EAAT3) mediates the reuptake of glutamate from the synaptic cleft to achieve rapid termination of synaptic transmission at glutamatergic synapses. In this study, we identified two interacting proteins of EAAT3 by mass spectrometry (MS) ARFGAP1 and ARF6. We explored the role of ARFGAP1 and ARF6 in the endocytosis of EAAT3. Our data revealed that ARFGAP1 plays a role in the recycling of EAAT3, by utilizing its GTPase activating protein (GAP) activity and ARF6 acting as the substrate. ARFGAP1 promotes cargo sorting of EAAT3 via a single phenylalanine residue (F508) located at the C-terminus of the transporter. ARFGAP1-promoted AP-2 dependent endocytosis is abolished upon neutralizing F508. We utilized a heterologous expression system to identify an additional motif in the C-terminus of EAAT3 that regulates its endocytosis. Impairment in endocytosis did not affect somatodendritic targeting in cultured hippocampal neurons. Our findings support a model where endocytosis of EAAT3 is a multifactorial event regulated by ARFGAP1, occurring via the C-terminus of the transporter, and is the first study to examine the role of ARFGAP1 in the endocytosis of a transport protein.
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Affiliation(s)
- Kusumika Saha
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria.,Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Descartes, Paris, France
| | - Jae-Won Yang
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Tina Hofmaier
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - SanthoshKannan Venkatesan
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Thomas Steinkellner
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Oliver Kudlacek
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Harald H Sitte
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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9
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Sieglin B, Maraschek M, Kudlacek O, Gude A, Treutterer W, Kölbl M, Lenz A. Rapid prototyping of advanced control schemes in ASDEX Upgrade. Fusion Engineering and Design 2020. [DOI: 10.1016/j.fusengdes.2020.111958] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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10
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Zhu R, Gobl J, Holy M, Kudlacek O, Sandtner W, Stockner T, Gruber HJ, Freissmuth M, Hauck Newman A, Sitte HH, Hinterdorfer P. Two Distinct Ligand Binding Sites in Monoamine Transporters Monitored by Nanopharmacological Force Sensing. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.3337] [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: 12/01/2022] Open
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11
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Niello M, Cintulova D, Hellsberg E, Jäntsch K, Holy M, Kudlacek O, Cozzi N, Baumann MH, Mihovilovic M, Ecker G, Sitte H. para
‐substituted methcathinones as selective and unselective inhibitors of human dopamine and serotonin transporters. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.656.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | | | | | - Nicholas Cozzi
- University of Wisconsin School of Medicine and Public HealthMadisonWI
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12
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Das AK, Kudlacek O, Baumgart F, Jaentsch K, Stockner T, Sitte HH, Schütz GJ. Dopamine transporter forms stable dimers in the live cell plasma membrane in a phosphatidylinositol 4,5-bisphosphate-independent manner. J Biol Chem 2019; 294:5632-5642. [PMID: 30705091 PMCID: PMC6462504 DOI: 10.1074/jbc.ra118.006178] [Citation(s) in RCA: 12] [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: 10/08/2018] [Revised: 01/28/2019] [Indexed: 01/01/2023] Open
Abstract
The human dopamine transporter (hDAT) regulates the level of the neurotransmitter dopamine (DA) in the synaptic cleft and recycles DA for storage in the presynaptic vesicular pool. Many neurotransmitter transporters exist as oligomers, but the physiological role of oligomerization remains unclear; for example, it has been speculated to be a prerequisite for amphetamine-induced release and protein trafficking. Previous studies point to an oligomeric quaternary structure of hDAT; however, the exact stoichiometry and the fraction of co-existing oligomeric states are not known. Here, we used single-molecule brightness analysis to quantify the degree of oligomerization of heterologously expressed hDAT fused to monomeric GFP (mGFP–hDAT) in Chinese hamster ovary (CHO) cells. We observed that monomers and dimers of mGFP–hDAT co-exist and that higher-order molecular complexes of mGFP–hDAT are absent at the plasma membrane. The mGFP–hDAT dimers were stable over several minutes, and the fraction of dimers was independent of the mGFP–hDAT surface density. Furthermore, neither oxidation nor depletion of cholesterol had any effect on the fraction of dimers. Unlike for the human serotonin transporter (hSERT), in which direct binding of phosphatidylinositol 4,5-bisphosphate (PIP2) stabilized the oligomers, the stability of mGFP–hDAT dimers was PIP2 independent.
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Affiliation(s)
- Anand Kant Das
- From the Institute of Applied Physics, TU Wien, Getreidemarkt 9, A-1060, Vienna and
| | - Oliver Kudlacek
- the Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
| | - Florian Baumgart
- From the Institute of Applied Physics, TU Wien, Getreidemarkt 9, A-1060, Vienna and
| | - Kathrin Jaentsch
- the Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
| | - Thomas Stockner
- the Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
| | - Harald H Sitte
- the Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
| | - Gerhard J Schütz
- From the Institute of Applied Physics, TU Wien, Getreidemarkt 9, A-1060, Vienna and
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13
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Mayer FP, Schmid D, Owens WA, Gould GG, Apuschkin M, Kudlacek O, Salzer I, Boehm S, Chiba P, Williams PH, Wu HH, Gether U, Koek W, Daws LC, Sitte HH. An unsuspected role for organic cation transporter 3 in the actions of amphetamine. Neuropsychopharmacology 2018; 43:2408-2417. [PMID: 29773909 PMCID: PMC6180071 DOI: 10.1038/s41386-018-0053-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 03/19/2018] [Accepted: 03/21/2018] [Indexed: 01/11/2023]
Abstract
Amphetamine abuse is a major public health concern for which there is currently no effective treatment. To develop effective treatments, the mechanisms by which amphetamine produces its abuse-related effects need to be fully understood. It is well known that amphetamine exerts its actions by targeting high-affinity transporters for monoamines, in particular the cocaine-sensitive dopamine transporter. Organic cation transporter 3 (OCT3) has recently been found to play an important role in regulating monoamine signaling. However, whether OCT3 contributes to the actions of amphetamine is unclear. We found that OCT3 is expressed in dopamine neurons. Then, applying a combination of in vivo, ex vivo, and in vitro approaches, we revealed that a substantial component of amphetamine's actions is OCT3-dependent and cocaine insensitive. Our findings support OCT3 as a new player in the actions of amphetamine and encourage investigation of this transporter as a potential new target for the treatment of psychostimulant abuse.
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Affiliation(s)
- Felix P. Mayer
- 0000 0000 9259 8492grid.22937.3dCenter for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Diethart Schmid
- 0000 0000 9259 8492grid.22937.3dCenter for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - W. Anthony Owens
- 0000 0001 0629 5880grid.267309.9Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229 USA
| | - Georgianna G. Gould
- 0000 0001 0629 5880grid.267309.9Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229 USA
| | - Mia Apuschkin
- 0000 0001 0674 042Xgrid.5254.6Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Panum Institute 18.6, 2200 Copenhagen N, Denmark
| | - Oliver Kudlacek
- 0000 0000 9259 8492grid.22937.3dCenter for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Isabella Salzer
- 0000 0000 9259 8492grid.22937.3dCenter for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Stefan Boehm
- 0000 0000 9259 8492grid.22937.3dCenter for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Peter Chiba
- 0000 0000 9259 8492grid.22937.3dInstitute of Medical Chemistry, Medical University of Vienna, 1090 Vienna, Austria
| | - Piper H. Williams
- 0000 0001 2156 6853grid.42505.36Department of Pediatrics, The Saban Research Institute, Children’s Hospital Los Angeles, Keck School of Medicine of USC, 4661 Sunset Blvd. Rm 307, Los Angeles, CA 90027 USA
| | - Hsiao-Huei Wu
- 0000 0001 2156 6853grid.42505.36Department of Pediatrics, The Saban Research Institute, Children’s Hospital Los Angeles, Keck School of Medicine of USC, 4661 Sunset Blvd. Rm 307, Los Angeles, CA 90027 USA
| | - Ulrik Gether
- 0000 0001 0674 042Xgrid.5254.6Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Panum Institute 18.6, 2200 Copenhagen N, Denmark
| | - Wouter Koek
- 0000 0001 0629 5880grid.267309.9Department of Psychiatry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229 USA ,0000 0001 0629 5880grid.267309.9Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229 USA
| | - Lynette C. Daws
- 0000 0001 0629 5880grid.267309.9Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229 USA ,0000 0001 0629 5880grid.267309.9Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229 USA
| | - Harald H. Sitte
- 0000 0000 9259 8492grid.22937.3dCenter for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria ,0000 0000 9259 8492grid.22937.3dCenter for Addiction Research and Science, Medical University Vienna, Waehringerstrasse 13 A, 1090 Vienna, Austria
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14
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Kudlacek O, Hofmaier T, Luf A, Mayer FP, Stockner T, Nagy C, Holy M, Freissmuth M, Schmid R, Sitte HH. Cocaine adulteration. J Chem Neuroanat 2017; 83-84:75-81. [PMID: 28619473 DOI: 10.1016/j.jchemneu.2017.06.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [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: 01/11/2017] [Revised: 05/03/2017] [Accepted: 06/10/2017] [Indexed: 12/20/2022]
Abstract
Cocaine is a naturally occurring and illicitly used psychostimulant drug. Cocaine acts at monoaminergic neurotransmitter transporters to block uptake of the monoamines, dopamine, serotonin and norepinephrine. The resulting increase of monoamines in the extracellular space underlies the positively reinforcing effects that cocaine users seek. In turn, this increase in monoamines underlies the development of addiction, and can also result in a number of severe side effects. Currently, cocaine is one of the most common illicit drugs available on the European market. However, cocaine is increasingly sold in impure forms. This trend is driven by cocaine dealers seeking to increase their profit margin by mixing ("cutting") cocaine with numerous other compounds ("adulterants"). Importantly, these undeclared compounds put cocaine consumers at risk, because consumers are not aware of the additional potential threats to their health. This review describes adulterants that have been identified in cocaine sold on the street market. Their typical pharmacological profile and possible reasons why these compounds can be used as cutting agents will be discussed. Since a subset of these adulterants has been found to exert effects similar to cocaine itself, we will discuss levamisole, the most frequently used cocaine cutting agent today, and its metabolite aminorex.
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Affiliation(s)
- Oliver Kudlacek
- Medical University Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Waehringerstrasse 13a, 1090 Vienna, Austria
| | - Tina Hofmaier
- Medical University Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Waehringerstrasse 13a, 1090 Vienna, Austria
| | - Anton Luf
- Medical University of Vienna, Clinical Department of Laboratory Medicine, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Felix P Mayer
- Medical University Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Waehringerstrasse 13a, 1090 Vienna, Austria
| | - Thomas Stockner
- Medical University Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Waehringerstrasse 13a, 1090 Vienna, Austria
| | - Constanze Nagy
- checkit!-Suchthilfe Wien gGmbH, Gumpendorferstraße8, 1060 Vienna, Austria
| | - Marion Holy
- Medical University Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Waehringerstrasse 13a, 1090 Vienna, Austria
| | - Michael Freissmuth
- Medical University Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Waehringerstrasse 13a, 1090 Vienna, Austria
| | - Rainer Schmid
- Medical University of Vienna, Clinical Department of Laboratory Medicine, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Harald H Sitte
- Medical University Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Waehringerstrasse 13a, 1090 Vienna, Austria; Center for Addiction Research and Science - Medical University Vienna, Waehringerstrasse 13A, 1090 Vienna, Austria.
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15
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Anderluh A, Hofmaier T, Klotzsch E, Kudlacek O, Stockner T, Sitte HH, Schütz GJ. Direct PIP 2 binding mediates stable oligomer formation of the serotonin transporter. Nat Commun 2017; 8:14089. [PMID: 28102201 PMCID: PMC5253637 DOI: 10.1038/ncomms14089] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [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: 05/19/2016] [Accepted: 11/28/2016] [Indexed: 12/30/2022] Open
Abstract
The human serotonin transporter (hSERT) mediates uptake of serotonin from the synaptic cleft and thereby terminates serotonergic signalling. We have previously found by single-molecule microscopy that SERT forms stable higher-order oligomers of differing stoichiometry at the plasma membrane of living cells. Here, we report that SERT oligomer assembly at the endoplasmic reticulum (ER) membrane follows a dynamic equilibration process, characterized by rapid exchange of subunits between different oligomers, and by a concentration dependence of the degree of oligomerization. After trafficking to the plasma membrane, however, the SERT stoichiometry is fixed. Stabilization of the oligomeric SERT complexes is mediated by the direct binding to phosphoinositide phosphatidylinositol-4,5-biphosphate (PIP2). The observed spatial decoupling of oligomer formation from the site of oligomer operation provides cells with the ability to define protein quaternary structures independent of protein density at the cell surface.
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Affiliation(s)
- Andreas Anderluh
- Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria
| | - Tina Hofmaier
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Waehringerstrasse 13A, Vienna 1090, Austria
| | - Enrico Klotzsch
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Oliver Kudlacek
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Waehringerstrasse 13A, Vienna 1090, Austria
| | - Thomas Stockner
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Waehringerstrasse 13A, Vienna 1090, Austria
| | - Harald H. Sitte
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Waehringerstrasse 13A, Vienna 1090, Austria
| | - Gerhard J. Schütz
- Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria
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16
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Seddik A, Geerke DP, Stockner T, Holy M, Kudlacek O, Cozzi NV, Ruoho AE, Sitte HH, Ecker GF. Combined Simulation and Mutation Studies to Elucidate Selectivity of Unsubstituted Amphetamine-like Cathinones at the Dopamine Transporter. Mol Inform 2016; 36. [PMID: 27860344 DOI: 10.1002/minf.201600094] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [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: 07/07/2016] [Accepted: 09/23/2016] [Indexed: 11/09/2022]
Abstract
The dopamine and serotonin transporter proteins (DAT, SERT) play a vital role in behavior and mental illness. Although their substrate transport has been studied extensively, the molecular basis of their selectivity is not completely understood yet. In this study, we exploit molecular dynamics simulations combined with mutagenesis studies to shed light on the driving factors for DAT-over-SERT selectivity of a set of cathinones. Results indicate that these compounds can adopt two binding modes of which one is more favorable. In addition, free energy calculations indicated the substrate binding site (S1) as the primary recognition site for these ligands. By simulating DAT with SERT-like mutations, we hypothesize unsubstituted cathinones to bind more favorably to DAT, due to a Val152 offering more space, as compared to the bulkier Ile172 in SERT. This was supported by uptake inhibition measurements, which showed an increase in activity in SERT-I172V.
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Affiliation(s)
- Amir Seddik
- University of Vienna, Department of Pharmaceutical Chemistry, Althanstrasse 14, 1090, Vienna, Austria
| | - Daan P Geerke
- AIMMS Division of Molecular Toxicology, Department of Chemistry and Pharmaceutical Sciences, VU University, De Boelelaan 1083, 1081, HV Amsterdam, the Netherlands
| | - Thomas Stockner
- Medical University of Vienna, Institute of Pharmacology, Center for Physiology and Pharmacology, Währingerstrasse 13a, 1090, Vienna, Austria
| | - Marion Holy
- Medical University of Vienna, Institute of Pharmacology, Center for Physiology and Pharmacology, Währingerstrasse 13a, 1090, Vienna, Austria
| | - Oliver Kudlacek
- Medical University of Vienna, Institute of Pharmacology, Center for Physiology and Pharmacology, Währingerstrasse 13a, 1090, Vienna, Austria
| | - Nicholas V Cozzi
- Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706
| | - Arnold E Ruoho
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706
| | - Harald H Sitte
- Medical University of Vienna, Institute of Pharmacology, Center for Physiology and Pharmacology, Währingerstrasse 13a, 1090, Vienna, Austria
| | - Gerhard F Ecker
- University of Vienna, Department of Pharmaceutical Chemistry, Althanstrasse 14, 1090, Vienna, Austria
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17
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Marchiori G, Finotti C, Kudlacek O, Villone F, Zanca P, Abate D, Cavazzana R, Jackson G, Luce T, Marrelli L. Design and operation of the RFX-mod plasma shape control system. Fusion Engineering and Design 2016. [DOI: 10.1016/j.fusengdes.2016.04.042] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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18
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Anderluh A, Hofmaier T, Klotzsch E, Kudlacek O, Stockner T, Sitte HH, Schütz GJ. Lipid Mediated Oligomeric Assembly of the Serotonin Transporter at the Plasma Membrane. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.1199] [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: 10/22/2022] Open
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19
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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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20
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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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21
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Saha K, Steinkellner T, Hofmaier T, Kudlacek O, Sucic S, Freissmuth M, Sitte H. Investigating EAAT3 trafficking through the secretory pathway. FASEB J 2015. [DOI: 10.1096/fasebj.29.1_supplement.565.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kusumika Saha
- Center for Physiology and Pharmacology Institute of PharmacologyWienAustria
| | - Thomas Steinkellner
- Center for Physiology and Pharmacology Institute of PharmacologyWienAustria
- Department of NeurosciencesUniversity of California San DiegoUnited States
| | - Tina Hofmaier
- Center for Physiology and Pharmacology Institute of PharmacologyWienAustria
| | - Oliver Kudlacek
- Center for Physiology and Pharmacology Institute of PharmacologyWienAustria
| | - Sonja Sucic
- Center for Physiology and Pharmacology Institute of PharmacologyWienAustria
| | - Michael Freissmuth
- Center for Physiology and Pharmacology Institute of PharmacologyWienAustria
| | - Harald Sitte
- Center for Physiology and Pharmacology Institute of PharmacologyWienAustria
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22
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Hofmaier T, Kudlacek O, Salzer I, Stockner T, Böhm S, Sitte H. The Impact of Phosphatidylinositol‐4,5‐bisophosphate (PIP2) on Serotonin Transport Function. FASEB J 2015. [DOI: 10.1096/fasebj.29.1_supplement.932.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Tina Hofmaier
- PharmacologyMedical University ViennaViennaAustriaAustria
| | | | - Isabella Salzer
- Neurophysiology and Neuropharmacology Medical University ViennaViennaAustriaAustria
| | | | - Stefan Böhm
- Neurophysiology and Neuropharmacology Medical University ViennaViennaAustriaAustria
| | - Harald Sitte
- PharmacologyMedical University ViennaViennaAustriaAustria
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23
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Steinkellner T, Mus L, Eisenrauch B, Constantinescu A, Leo D, Konrad L, Rickhag M, Sørensen G, Efimova EV, Kong E, Willeit M, Sotnikova TD, Kudlacek O, Gether U, Freissmuth M, Pollak DD, Gainetdinov RR, Sitte HH. In vivo amphetamine action is contingent on αCaMKII. Neuropsychopharmacology 2014; 39:2681-93. [PMID: 24871545 PMCID: PMC4207348 DOI: 10.1038/npp.2014.124] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 05/01/2014] [Accepted: 05/05/2014] [Indexed: 11/09/2022]
Abstract
Addiction to psychostimulants (ie, amphetamines and cocaine) imposes a major socioeconomic burden. Prevention and treatment represent unmet medical needs, which may be addressed, if the mechanisms underlying psychostimulant action are understood. Cocaine acts as a blocker at the transporters for dopamine (DAT), serotonin (SERT), and norepinephrine (NET), but amphetamines are substrates that do not only block the uptake of monoamines but also induce substrate efflux by promoting reverse transport. Reverse transport has been a focus of research for decades but its mechanistic basis still remains enigmatic. Recently, transporter-interacting proteins were found to regulate amphetamine-triggered reverse transport: calmodulin kinase IIα (αCaMKII) is a prominent example, because it binds the carboxyl terminus of DAT, phosphorylates its amino terminus, and supports amphetamine-induced substrate efflux in vitro. Here, we investigated whether, in vivo, the action of amphetamine was contingent on the presence of αCaMKII by recording the behavioral and neurochemical effects of amphetamine. Measurement of dopamine efflux in the dorsal striatum by microdialysis revealed that amphetamine induced less dopamine efflux in mice lacking αCaMKII. Consistent with this observation, the acute locomotor responses to amphetamine were also significantly blunted in αCaMKII-deficient mice. In addition, while the rewarding properties of amphetamine were preserved in αCaMKII-deficient mice, their behavioral sensitization to amphetamine was markedly reduced. Our findings demonstrate that amphetamine requires the presence of αCaMKII to elicit a full-fledged effect on DAT in vivo: αCaMKII does not only support acute amphetamine-induced dopamine efflux but is also important in shaping the chronic response to amphetamine.
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Affiliation(s)
- Thomas Steinkellner
- Institute of Pharmacology, Center for
Physiology and Pharmacology, Medical University Vienna, Waehringer Strasse,
Vienna, Austria
| | - Liudmilla Mus
- Department of Neuroscience and Brain
Technologies, Istituto Italiano di Tecnologia (IIT), Via Morego,
Genova, Italy,Department of Psychopharmacology,
Institute of Pharmacology, Pavlov Medical University, St
Petersburg, Russia
| | - Birgit Eisenrauch
- Institute of Pharmacology, Center for
Physiology and Pharmacology, Medical University Vienna, Waehringer Strasse,
Vienna, Austria
| | - Andreea Constantinescu
- Institute of Pharmacology, Center for
Physiology and Pharmacology, Medical University Vienna, Waehringer Strasse,
Vienna, Austria
| | - Damiana Leo
- Department of Neuroscience and Brain
Technologies, Istituto Italiano di Tecnologia (IIT), Via Morego,
Genova, Italy
| | - Lisa Konrad
- Institute of Pharmacology, Center for
Physiology and Pharmacology, Medical University Vienna, Waehringer Strasse,
Vienna, Austria
| | - Mattias Rickhag
- Molecular Neuropharmacology and Genetics
Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and
Medical Sciences, The Panum Institute, University of Copenhagen,
Copenhagen, Denmark
| | - Gunnar Sørensen
- Molecular Neuropharmacology and Genetics
Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and
Medical Sciences, The Panum Institute, University of Copenhagen,
Copenhagen, Denmark
| | - Evgenia V Efimova
- Skolkovo Institute of Science and
Technology (Skoltech), Skolkovo, Moscow,
Russia
| | - Eryan Kong
- Department of Neurophysiology and
Neuropharmacology, Center for Physiology and Pharmacology, Medical University
Vienna, Waehringer Strasse, Vienna, Austria
| | - Matthäus Willeit
- Department of Psychiatry and
Psychotherapy, Medical University of Vienna, Waehringer Guertel,
Vienna, Austria
| | - Tatyana D Sotnikova
- Department of Neuroscience and Brain
Technologies, Istituto Italiano di Tecnologia (IIT), Via Morego,
Genova, Italy
| | - Oliver Kudlacek
- Institute of Pharmacology, Center for
Physiology and Pharmacology, Medical University Vienna, Waehringer Strasse,
Vienna, Austria
| | - Ulrik Gether
- Molecular Neuropharmacology and Genetics
Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and
Medical Sciences, The Panum Institute, University of Copenhagen,
Copenhagen, Denmark
| | - Michael Freissmuth
- Institute of Pharmacology, Center for
Physiology and Pharmacology, Medical University Vienna, Waehringer Strasse,
Vienna, Austria
| | - Daniela D Pollak
- Department of Neurophysiology and
Neuropharmacology, Center for Physiology and Pharmacology, Medical University
Vienna, Waehringer Strasse, Vienna, Austria
| | - Raul R Gainetdinov
- Department of Neuroscience and Brain
Technologies, Istituto Italiano di Tecnologia (IIT), Via Morego,
Genova, Italy,Skolkovo Institute of Science and
Technology (Skoltech), Skolkovo, Moscow,
Russia,Faculty of Biology and Soil Science, St
Petersburg State University, St Petersburg,
Russia
| | - Harald H Sitte
- Institute of Pharmacology, Center for
Physiology and Pharmacology, Medical University Vienna, Waehringer Strasse,
Vienna, Austria,Institute of Pharmacology, Center for Physiology and
Pharmacology, Medical University Vienna, Waehringer Strasse 13A,
Vienna
1090, Austria, Tel: +43 1 40160 31323, Fax: +43 1
40160 931300, E-mail:
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24
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Fenollar-Ferrer C, Stockner T, Schwarz TC, Pal A, Gotovina J, Hofmaier T, Jayaraman K, Adhikary S, Kudlacek O, Mehdipour AR, Tavoulari S, Rudnick G, Singh SK, Konrat R, Sitte HH, Forrest LR. Structure and regulatory interactions of the cytoplasmic terminal domains of serotonin transporter. Biochemistry 2014; 53:5444-60. [PMID: 25093911 PMCID: PMC4147951 DOI: 10.1021/bi500637f] [Citation(s) in RCA: 48] [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] [Indexed: 12/20/2022]
Abstract
![]()
Uptake
of neurotransmitters by sodium-coupled monoamine transporters
of the NSS family is required for termination of synaptic transmission.
Transport is tightly regulated by protein–protein interactions
involving the small cytoplasmic segments at the amino-
and carboxy-terminal ends of the transporter. Although structures
of homologues provide information about the transmembrane regions
of these transporters,
the structural arrangement of the terminal domains remains largely
unknown. Here, we combined molecular modeling, biochemical, and biophysical
approaches in an iterative manner to
investigate the structure of the 82-residue N-terminal and 30-residue
C-terminal domains of human serotonin transporter (SERT). Several
secondary structures were predicted in these domains, and structural
models were built using the Rosetta fragment-based methodology. One-dimensional 1H nuclear magnetic resonance and circular dichroism spectroscopy
supported the presence of helical elements in the isolated SERT N-terminal
domain. Moreover, introducing helix-breaking residues within those
elements altered the fluorescence resonance energy transfer signal
between terminal cyan fluorescent protein and yellow fluorescent protein
tags attached to full-length SERT, consistent with the notion that
the fold of the terminal domains is relatively well-defined. Full-length
models of SERT that are consistent with these and published
experimental data were generated. The resultant models predict confined
loci for the terminal domains and predict that they move apart during
the transport-related conformational cycle, as predicted by structures
of homologues and by the “rocking
bundle” hypothesis, which is consistent with spectroscopic
measurements. The models also suggest the nature of binding to regulatory
interaction partners. This study provides a structural context for
functional and regulatory mechanisms involving SERT terminal domains.
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Affiliation(s)
- Cristina Fenollar-Ferrer
- Computational Structural Biology Group, Max Planck Institute of Biophysics , 60438 Frankfurt am Main, Germany
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25
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Sitte H, Hofmaier T, Anderluh A, Kudlacek O, Klotzsch E, Yang J, Geier P, Schicker K, Böhm S, Schütz G. The molecular mechanism of amphetamine action (358.2). FASEB J 2014. [DOI: 10.1096/fasebj.28.1_supplement.358.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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26
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Janky F, Havlicek J, Batista A, Kudlacek O, Seidl J, Neto A, Pipek J, Hron M, Mikulin O, Duarte A, Carvalho B, Stockel J, Panek R. Upgrade of the COMPASS tokamak real-time control system. Fusion Engineering and Design 2014. [DOI: 10.1016/j.fusengdes.2013.12.042] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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27
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Thurner P, Gsandtner I, Kudlacek O, Choquet D, Nanoff C, Freissmuth M, Zezula J. A two-state model for the diffusion of the A2A adenosine receptor in hippocampal neurons: agonist-induced switch to slow mobility is modified by synapse-associated protein 102 (SAP102). J Biol Chem 2014; 289:9263-74. [PMID: 24509856 PMCID: PMC3979375 DOI: 10.1074/jbc.m113.505685] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The A2A receptor is a class A/rhodopsin-like G protein-coupled receptor. Coupling to its cognate protein, Gs, occurs via restricted collision coupling and is contingent on the presence of cholesterol. Agonist activation slows diffusion of the A2A adenosine receptor in the lipid bilayer. We explored the contribution of the hydrophobic core and of the extended C terminus by examining diffusion of quantum dot-labeled receptor variants in dissociated hippocampal neurons. Single particle tracking of the A2A receptor(1–311), which lacks the last 101 residues, revealed that agonist-induced confinement was abolished and that the agonist-induced decrease in diffusivity was reduced substantially. A fragment comprising the SH3 domain and the guanylate kinase domain of synapse-associated protein 102 (SAP102) was identified as a candidate interactor that bound to the A2A receptor C terminus. Complex formation between the A2A receptor and SAP102 was verified by coimmunoprecipitation and by tracking its impact on receptor diffusion. An analysis of all trajectories by a hidden Markov model was consistent with two diffusion states where agonist activation reduced the transition between the two states and, thus, promoted the accumulation of the A2A receptor in the compartment with slow mobility. Overexpression of SAP102 precluded the access of the A2A receptor to a compartment with restricted mobility. In contrast, a mutated A2A receptor (with 383DVELL387 replaced by RVRAA) was insensitive to the action of SAP102. These observations show that the hydrophobic core per se does not fully account for the agonist-promoted change in mobility of the A2A receptor. The extended carboxyl terminus allows for regulatory input by scaffolding molecules such as SAP102.
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Affiliation(s)
- Patrick Thurner
- From the Institute for Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Währinger Str. 13a, 1090 Vienna, Austria and
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28
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Anderluh A, Klotzsch E, Reismann AWAF, Brameshuber M, Kudlacek O, Newman AH, Sitte HH, Schütz GJ. Single molecule analysis reveals coexistence of stable serotonin transporter monomers and oligomers in the live cell plasma membrane. J Biol Chem 2014; 289:4387-94. [PMID: 24394416 DOI: 10.1074/jbc.m113.531632] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [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: 02/04/2023] Open
Abstract
The human serotonin transporter (hSERT) is responsible for the termination of synaptic serotonergic signaling. Although there is solid evidence that SERT forms oligomeric complexes, the exact stoichiometry of the complexes and the fractions of different coexisting oligomeric states still remain enigmatic. Here we used single molecule fluorescence microscopy to obtain the oligomerization state of the SERT via brightness analysis of single diffraction-limited fluorescent spots. Heterologously expressed SERT was labeled either with the fluorescent inhibitor JHC 1-64 or via fusion to monomeric GFP. We found a variety of oligomerization states of membrane-associated transporters, revealing molecular associations larger than dimers and demonstrating the coexistence of different degrees of oligomerization in a single cell; the data are in agreement with a linear aggregation model. Furthermore, oligomerization was found to be independent of SERT surface density, and oligomers remained stable over several minutes in the live cell plasma membrane. Together, the results indicate kinetic trapping of preformed SERT oligomers at the plasma membrane.
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Affiliation(s)
- Andreas Anderluh
- From the Institute of Applied Physics, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
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29
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Sohail A, Kudlacek O, Daerr M, Stolt-Bergner P, Ecker G, Freissmuth M, Wanner K, Stockner T, Sandtner W, Sitte H. Unfolding the Structure of LeuT Employing Luminescence Resonance Energy Transfer. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.1515] [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: 10/23/2022] Open
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30
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Thurner P, Stary-Weinzinger A, Gafar H, Gawali VS, Kudlacek O, Zezula J, Hilber K, Boehm S, Sandtner W, Koenig X. Mechanism of hERG channel block by the psychoactive indole alkaloid ibogaine. J Pharmacol Exp Ther 2013; 348:346-58. [PMID: 24307198 DOI: 10.1124/jpet.113.209643] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [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
Ibogaine is a psychoactive indole alkaloid. Its use as an antiaddictive agent has been accompanied by QT prolongation and cardiac arrhythmias, which are most likely caused by human ether a go-go-related gene (hERG) potassium channel inhibition. Therefore, we studied in detail the interaction of ibogaine with hERG channels heterologously expressed in mammalian kidney tsA-201 cells. Currents through hERG channels were blocked regardless of whether ibogaine was applied via the extracellular or intracellular solution. The extent of inhibition was determined by the relative pH values. Block occurred during activation of the channels and was not observed for resting channels. With increasing depolarizations, ibogaine block grew and developed faster. Steady-state activation and inactivation of the channel were shifted to more negative potentials. Deactivation was slowed, whereas inactivation was accelerated. Mutations in the binding site reported for other hERG channel blockers (Y652A and F656A) reduced the potency of ibogaine, whereas an inactivation-deficient double mutant (G628C/S631C) was as sensitive as wild-type channels. Molecular drug docking indicated binding within the inner cavity of the channel independently of the protonation of ibogaine. Experimental current traces were fit to a kinetic model of hERG channel gating, revealing preferential binding of ibogaine to the open and inactivated state. Taken together, these findings show that ibogaine blocks hERG channels from the cytosolic side either in its charged form alone or in company with its uncharged form and alters the currents by changing the relative contribution of channel states over time.
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Affiliation(s)
- Patrick Thurner
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria (H.G., V.S.G., K.H., S.B., X.K.), Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Vienna, Austria (P.T., O.K., J.Z., W.S.), Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (A.S.-W.)
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31
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Hofmaier T, Luf A, Seddik A, Stockner T, Holy M, Freissmuth M, Ecker GF, Schmid R, Sitte HH, Kudlacek O. Aminorex, a metabolite of the cocaine adulterant levamisole, exerts amphetamine like actions at monoamine transporters. Neurochem Int 2013; 73:32-41. [PMID: 24296074 PMCID: PMC4077236 DOI: 10.1016/j.neuint.2013.11.010] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 11/22/2013] [Accepted: 11/24/2013] [Indexed: 11/17/2022]
Abstract
We quantified adulterants in street drugs sold as cocaine. We analyzed effects of the most common adulterant levamisole, on neurotransmitter transporters. Differences in the selectivity of levamisole can be explained by homology modelling and docking. Aminorex, a metabolite of levamisole, modulates neurotransmitter transporters directly. Depending on the transporter, aminorex acts as a blocker or as a releaser.
Psychostimulants such as amphetamine and cocaine are illicitly used drugs that act on neurotransmitter transporters for dopamine, serotonin or norepinephrine. These drugs can by themselves already cause severe neurotoxicity. However, an additional health threat arises from adulterant substances which are added to the illicit compound without declaration. One of the most frequently added adulterants in street drugs sold as cocaine is the anthelmintic drug levamisole. We tested the effects of levamisole on neurotransmitter transporters heterologously expressed in HEK293 cells. Levamisole was 100 and 300-fold less potent than cocaine in blocking norepinephrine and dopamine uptake, and had only very low affinity for the serotonin transporter. In addition, levamisole did not trigger any appreciable substrate efflux. Because levamisole and cocaine are frequently co-administered, we searched for possible allosteric effects; at 30 μM, a concentration at which levamisole displayed already mild effects on norepinephrine transport it did not enhance the inhibitory action of cocaine. Levamisole is metabolized to aminorex, a formerly marketed anorectic drug, which is classified as an amphetamine-like substance. We examined the uptake-inhibitory and efflux-eliciting properties of aminorex and found it to exert strong effects on all three neurotransmitter transporters in a manner similar to amphetamine. We therefore conclude that while the adulterant levamisole itself has only moderate effects on neurotransmitter transporters, its metabolite aminorex may exert distinct psychostimulant effects by itself. Given that the half-time of levamisole and aminorex exceeds that of cocaine, it may be safe to conclude that after the cocaine effect “fades out” the levamisole/aminorex effect “kicks in”.
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Affiliation(s)
- Tina Hofmaier
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13A, 1090 Vienna, Austria
| | - Anton Luf
- Clinical Department of Laboratory Medicine, Medical University of Vienna, Waehringer Guertel 10-20, 1090 Vienna, Austria
| | - Amir Seddik
- University of Vienna, Department of Medicinal Chemistry, Althanstrasse 14, 1090 Vienna, Austria
| | - Thomas Stockner
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13A, 1090 Vienna, Austria
| | - Marion Holy
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13A, 1090 Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13A, 1090 Vienna, Austria
| | - Gerhard F Ecker
- University of Vienna, Department of Medicinal Chemistry, Althanstrasse 14, 1090 Vienna, Austria
| | - Rainer Schmid
- Clinical Department of Laboratory Medicine, Medical University of Vienna, Waehringer Guertel 10-20, 1090 Vienna, Austria
| | - Harald H Sitte
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13A, 1090 Vienna, Austria.
| | - Oliver Kudlacek
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13A, 1090 Vienna, Austria
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32
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Bergmayr C, Thurner P, Keuerleber S, Kudlacek O, Nanoff C, Freissmuth M, Gruber CW. Recruitment of a cytoplasmic chaperone relay by the A2A adenosine receptor. J Biol Chem 2013; 288:28831-44. [PMID: 23965991 PMCID: PMC3789979 DOI: 10.1074/jbc.m113.464776] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [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: 11/18/2022] Open
Abstract
The adenosine A2A receptor is a prototypical rhodopsin-like G protein-coupled receptor but has several unique structural features, in particular a long C terminus (of >120 residues) devoid of a palmitoylation site. It is known to interact with several accessory proteins other than those canonically involved in signaling. However, it is evident that many more proteins must interact with the A2A receptor, if the trafficking trajectory of the receptor is taken into account from its site of synthesis in the endoplasmic reticulum (ER) to its disposal by the lysosome. Affinity-tagged versions of the A2A receptor were expressed in HEK293 cells to identify interacting partners residing in the ER by a proteomics approach based on tandem affinity purification. The receptor-protein complexes were purified in quantities sufficient for analysis by mass spectrometry. We identified molecular chaperones (heat-shock proteins HSP90α and HSP70-1A) that interact with and retain partially folded A2A receptor prior to ER exit. Complex formation between the A2A receptor and HSP90α (but not HSP90β) and HSP70-1A was confirmed by co-affinity precipitation. HSP90 inhibitors also enhanced surface expression of the receptor in PC12 cells, which endogenously express the A2A receptor. Finally, proteins of the HSP relay machinery (e.g. HOP/HSC70-HSP90 organizing protein and P23/HSP90 co-chaperone) were recovered in complexes with the A2A receptor. These observations are consistent with the proposed chaperone/coat protein complex II exchange model. This posits that cytosolic HSP proteins are sequentially recruited to folding intermediates of the A2A receptor. Release of HSP90 is required prior to recruitment of coat protein complex II components. This prevents premature ER export of partially folded receptors.
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Affiliation(s)
- Christian Bergmayr
- From the Institute for Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
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33
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Stockner T, Montgomery TR, Kudlacek O, Weissensteiner R, Ecker GF, Freissmuth M, Sitte HH. Mutational analysis of the high-affinity zinc binding site validates a refined human dopamine transporter homology model. PLoS Comput Biol 2013; 9:e1002909. [PMID: 23436987 PMCID: PMC3578762 DOI: 10.1371/journal.pcbi.1002909] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [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: 06/12/2012] [Accepted: 12/16/2012] [Indexed: 11/24/2022] Open
Abstract
The high-resolution crystal structure of the leucine transporter (LeuT) is frequently used as a template for homology models of the dopamine transporter (DAT). Although similar in structure, DAT differs considerably from LeuT in a number of ways: (i) when compared to LeuT, DAT has very long intracellular amino and carboxyl termini; (ii) LeuT and DAT share a rather low overall sequence identity (22%) and (iii) the extracellular loop 2 (EL2) of DAT is substantially longer than that of LeuT. Extracellular zinc binds to DAT and restricts the transporter‚s movement through the conformational cycle, thereby resulting in a decrease in substrate uptake. Residue H293 in EL2 praticipates in zinc binding and must be modelled correctly to allow for a full understanding of its effects. We exploited the high-affinity zinc binding site endogenously present in DAT to create a model of the complete transmemberane domain of DAT. The zinc binding site provided a DAT-specific molecular ruler for calibration of the model. Our DAT model places EL2 at the transporter lipid interface in the vicinity of the zinc binding site. Based on the model, D206 was predicted to represent a fourth co-ordinating residue, in addition to the three previously described zinc binding residues H193, H375 and E396. This prediction was confirmed by mutagenesis: substitution of D206 by lysine and cysteine affected the inhibitory potency of zinc and the maximum inhibition exerted by zinc, respectively. Conversely, the structural changes observed in the model allowed for rationalizing the zinc-dependent regulation of DAT: upon binding, zinc stabilizes the outward-facing state, because its first coordination shell can only be completed in this conformation. Thus, the model provides a validated solution to the long extracellular loop and may be useful to address other aspects of the transport cycle. The dopamine transporter (DAT) regulates dopaminergic neurotransmission in the brain and is implicated in numerous human disease states. DAT is unique among the monoamine neurotransmitter transporter family because its substrate transport is inhibited by extracellular zinc. DAT homology models rely upon the crystal structure of LeuT solved in 2005. LeuT and DAT share a relatively low overall sequence identity of 22%. In addition, the length of the second extracellular loop of DAT exceeds that of LeuT by 21 residues. The zinc binding site cannot be directly modeled from the LeuT template alone because of these differences. Current available homology models of DAT focused on substrate or inhibitor binding rather than on the second extracellular loop. We exploited the specificity of the zinc binding site to build and calibrate a DAT homology model of the complete transmembrane domain. Our model predicted that the zinc binding site in DAT consists of four zinc co-ordinating residues rather than three that had been previously identified. We verified this hypothesis by site-directed mutagenesis and uptake inhibition studies.
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Affiliation(s)
- Thomas Stockner
- Center of Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Vienna, Austria
| | - Therese R. Montgomery
- Center of Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Vienna, Austria
| | - Oliver Kudlacek
- Center of Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Vienna, Austria
| | | | - Gerhard F. Ecker
- Department of Medicinal Chemistry, University of Vienna, Vienna, Austria
| | - Michael Freissmuth
- Center of Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Vienna, Austria
| | - Harald H. Sitte
- Center of Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Vienna, Austria
- * E-mail:
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Sucic S, Koban F, El-Kasaby A, Kudlacek O, Stockner T, Sitte HH, Freissmuth M. Switching the clientele: a lysine residing in the C terminus of the serotonin transporter specifies its preference for the coat protein complex II component SEC24C. J Biol Chem 2013; 288:5330-41. [PMID: 23288844 PMCID: PMC3581386 DOI: 10.1074/jbc.m112.408237] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [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: 11/24/2022] Open
Abstract
The serotonin transporter (SERT) maintains serotonergic neurotransmission via rapid reuptake of serotonin from the synaptic cleft. SERT relies exclusively on the coat protein complex II component SEC24C for endoplasmic reticulum (ER) export. The closely related transporters for noradrenaline and dopamine depend on SEC24D. Here, we show that discrimination between SEC24C and SEC24D is specified by the residue at position +2 downstream from the ER export motif (607RI608 in SERT). Substituting Lys610 with tyrosine, the corresponding residue found in the noradrenaline and dopamine transporters, switched the SEC24 isoform preference: SERT-K610Y relied solely on SEC24D to reach the cell surface. This analysis was extended to other SLC6 (solute carrier 6) transporter family members: siRNA-dependent depletion of SEC24C, but not of SEC24D, reduced surface levels of the glycine transporter-1a, the betaine/GABA transporter and the GABA transporter-4. Experiments with dominant negative versions of SEC24C and SEC24D recapitulated these findings. We also verified that the presence of two ER export motifs (in concatemers of SERT and GABA transporter-1) supported recruitment of both SEC24C and SEC24D. To the best of our knowledge, this is the first report to document a change in SEC24 specificity by mutation of a single residue in the client protein. Our observations allowed for deducing a rule for SLC6 family members: a hydrophobic residue (Tyr or Val) in the +2 position specifies interaction with SEC24D, and a hydrophilic residue (Lys, Asn, or Gln) recruits SEC24C. Variations in SEC24C are linked to neuropsychiatric disorders. The present findings provide a mechanistic explanation. Variations in SEC24C may translate into distinct surface levels of neurotransmitter transporters.
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Affiliation(s)
- Sonja Sucic
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
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35
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Kudlacek O, Dönmez Y, Stockner T. ABC transporters of the liver fluke Fasciola hepatica. BMC Pharmacol Toxicol 2012. [PMCID: PMC3506343 DOI: 10.1186/2050-6511-13-s1-a76] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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36
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Sohail A, Bulling S, Stolt-Bergner P, Kudlacek O, Ecker GF, Freissmuth M, Stockner T, Sitte HH, Sandtner W. Decrypting structural and functional changes in LeuTAaat atomic level employing LRET. BMC Pharmacol Toxicol 2012. [PMCID: PMC3506313 DOI: 10.1186/2050-6511-13-s1-a53] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
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37
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Steinkellner T, Montgomery T, Yang JW, Rickhag M, Sucic S, Elgersma Y, Kudlacek O, Freissmuth M, Gether U, Sitte HH. Calmodulin kinase II regulates amphetamine-induced reverse transport in dopamine and serotonin transporters. BMC Pharmacol Toxicol 2012. [PMCID: PMC3506316 DOI: 10.1186/2050-6511-13-s1-a56] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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38
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Steinkellner T, Yang JW, Montgomery TR, Chen WQ, Winkler MT, Sucic S, Lubec G, Freissmuth M, Elgersma Y, Sitte HH, Kudlacek O. Ca(2+)/calmodulin-dependent protein kinase IIα (αCaMKII) controls the activity of the dopamine transporter: implications for Angelman syndrome. J Biol Chem 2012; 287:29627-35. [PMID: 22778257 PMCID: PMC3436163 DOI: 10.1074/jbc.m112.367219] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [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: 11/06/2022] Open
Abstract
The dopamine transporter (DAT) is a crucial regulator of dopaminergic neurotransmission, controlling the length and brevity of dopaminergic signaling. DAT is also the primary target of psychostimulant drugs such as cocaine and amphetamines. Conversely, methylphenidate and amphetamine are both used clinically in the treatment of attention-deficit hyperactivity disorder and narcolepsy. The action of amphetamines, which induce transport reversal, relies primarily on the ionic composition of the intra- and extracellular milieus. Recent findings suggest that DAT interacting proteins may also play a significant role in the modulation of reverse dopamine transport. The pharmacological inhibition of the serine/threonine kinase αCaMKII attenuates amphetamine-triggered DAT-mediated 1-methyl-4-phenylpyridinium (MPP(+)) efflux. More importantly, αCaMKII has also been shown to bind DAT in vitro and is therefore believed to be an important player within the DAT interactome. Herein, we show that αCaMKII co-immunoprecipitates with DAT in mouse striatal synaptosomes. Mice, which lack αCaMKII or which express a permanently self-inhibited αCaMKII (αCaMKII(T305D)), exhibit significantly reduced amphetamine-triggered DAT-mediated MPP(+) efflux. Additionally, we investigated mice that mimic a neurogenetic disease known as Angelman syndrome. These mice possess reduced αCaMKII activity. Angelman syndrome mice demonstrated an impaired DAT efflux function, which was comparable with that of the αCaMKII mutant mice, indicating that DAT-mediated dopaminergic signaling is affected in Angelman syndrome.
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Affiliation(s)
- Thomas Steinkellner
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
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39
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Bergmayr C, Nanoff C, Kudlacek O, Freissmuth M, Gruber CW. The folding interactome of GPCRs. BMC Pharmacol 2011. [PMCID: PMC3194276 DOI: 10.1186/1471-2210-11-s2-a41] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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40
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Sucic S, Kern C, Vidovic D, Sarker S, Kudlacek O, Sitte HH, Freissmuth M. Truncations in the amino terminus reveal a region key to supporting amphetamine-induced efflux by the human serotonin transporter. BMC Pharmacol 2011. [PMCID: PMC3194253 DOI: 10.1186/1471-2210-11-s2-a20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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41
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El-Kasaby A, Stockner T, Kudlacek O. ABC transporters of Fasciola hepatica as putative drug targets. BMC Pharmacol 2011. [PMCID: PMC3194270 DOI: 10.1186/1471-2210-11-s2-a36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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42
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Sucic S, El-Kasaby A, Kudlacek O, Sarker S, Sitte HH, Marin P, Freissmuth M. The serotonin transporter is an exclusive client of the coat protein complex II (COPII) component SEC24C. J Biol Chem 2011; 286:16482-90. [PMID: 21454670 PMCID: PMC3091253 DOI: 10.1074/jbc.m111.230037] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [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: 11/06/2022] Open
Abstract
The transporters for serotonin (SERT), dopamine, and noradrenaline have a conserved hydrophobic core but divergent N and C termini. The C terminus harbors the binding site for the coat protein complex II (COPII) cargo-binding protein SEC24. Here we explored which SEC24 isoform was required for export of SERT from the endoplasmic reticulum (ER). Three lines of evidence argue that SERT can only exit the ER by recruiting SEC24C: (i) Mass spectrometry showed that a peptide corresponding to the C terminus of SERT recruited SEC24C-containing COPII complexes from mouse brain lysates. (ii) Depletion of individual SEC24 isoforms by siRNAs revealed that SERT was trapped in the ER only if SEC24C was down-regulated, in both, cells that expressed SERT endogenously or after transfection. The combination of all siRNAs was not more effective than that directed against SEC24C. A SERT mutant in which the SEC24C-binding motif ((607)RI(608)) was replaced by alanine was insensitive to down-regulation of SEC24C levels. (iii) Overexpression of a SEC24C variant with a mutation in the candidate cargo-binding motif (SEC24C-D796V/D797N) but not of the corresponding mutant SEC24D-D733V/D734N reduced SERT surface levels. In contrast, noradrenaline and dopamine transporters and the more distantly related GABA transporter 1 relied on SEC24D for ER export. These observations demonstrate that closely related transporters are exclusive client cargo proteins for different SEC24 isoforms. The short promoter polymorphism results in reduced SERT cell surface levels and renders affected individuals more susceptible to depression. By inference, variations in the Sec24C gene may also affect SERT cell surface levels and thus be linked to mood disorders.
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Affiliation(s)
- Sonja Sucic
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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Steinkellner T, Kudlacek O, Freissmuth M, Elgersma Y, Sitte H. Calmodulin kinase II regulates amphetamine-induced reverse transport in the dopamine transporter: implications for the importance of the dopamine transporter in Angelman syndrome. BMC Pharmacol 2010. [PMCID: PMC3016528 DOI: 10.1186/1471-2210-10-s1-a19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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44
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El-Kasaby A, Just H, Sitte H, Kudlacek O, Freissmuth M. The role of the carboxyl terminus in folding of the serotonin transporter. BMC Pharmacol 2010. [PMCID: PMC3016527 DOI: 10.1186/1471-2210-10-s1-a18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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45
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Bergmayr C, Nanoff C, Kudlacek O, Gruber C. The interactome of the A2A adenosine receptor in vitro and in vivo. BMC Pharmacol 2010. [PMCID: PMC3016536 DOI: 10.1186/1471-2210-10-s1-a26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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46
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El-Kasaby A, Just H, Malle E, Stolt-Bergner PC, Sitte HH, Freissmuth M, Kudlacek O. Mutations in the carboxyl-terminal SEC24 binding motif of the serotonin transporter impair folding of the transporter. J Biol Chem 2010; 285:39201-10. [PMID: 20889976 PMCID: PMC2998113 DOI: 10.1074/jbc.m110.118000] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [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: 11/21/2022] Open
Abstract
The serotonin transporter (SERT) is a member of the SLC6 family of solute carriers. SERT plays a crucial role in synaptic neurotransmission by retrieving released serotonin. The intracellular carboxyl terminus of various neurotransmitter transporters has been shown to be important for the correct delivery of SLC6 family members to the cell surface. Here we studied the importance of the C terminus in trafficking and folding of human SERT. Serial truncations followed by mutagenesis identified sequence spots (PG601,602, RII607–609) within the C terminus relevant for export of SERT from the endoplasmic reticulum (ER). RI607,608 is homologous to the RL-motif that in other SLC6 family members provides a docking site for the COPII component Sec24D. The primary defect resulting from mutation at PG601,602 and RI607,608 was impaired folding, because mutated transporters failed to bind the inhibitor [3H]imipramine. In contrast, when retained in the ER (e.g. by dominant negative Sar1) the wild type transporter bound [3H]imipramine with an affinity comparable to that of the surface-expressed transporter. SERT-RI607,608AA and SERT-RII607–609AAA were partially rescued by treatment of cells with the nonspecific chemical chaperone DMSO or the specific pharmacochaperone ibogaine (which binds to the inward facing conformation of SERT) but not by other classes of ligands (inhibitors, substrates, amphetamines). These observations (i) demonstrate an hitherto unappreciated role of the C terminus in the folding of SERT, (ii) indicates that the folding trajectory proceeds via an inward facing intermediate, and (iii) suggest a model where the RI-motif plays a crucial role in preventing premature Sec24-recruitment and export of incorrectly folded transporters.
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Affiliation(s)
- Ali El-Kasaby
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Währinger Str. 13a, A-1090 Vienna, Austria
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Sucic S, Dallinger S, Zdrazil B, Weissensteiner R, Jørgensen TN, Holy M, Kudlacek O, Seidel S, Cha JH, Gether U, Newman AH, Ecker GF, Freissmuth M, Sitte HH. The N terminus of monoamine transporters is a lever required for the action of amphetamines. J Biol Chem 2010; 285:10924-38. [PMID: 20118234 PMCID: PMC2856298 DOI: 10.1074/jbc.m109.083154] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [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: 11/24/2022] Open
Abstract
The serotonin transporter (SERT) terminates neurotransmission by removing serotonin from the synaptic cleft. In addition, it is the site of action of antidepressants (which block the transporter) and of amphetamines (which induce substrate efflux). We explored the functional importance of the N terminus in mediating the action of amphetamines by focusing initially on the highly conserved threonine residue at position 81, a candidate site for phosphorylation by protein kinase C. Molecular dynamics simulations of the wild type SERT, compared with its mutations SERTT81A and SERTT81D, suggested structural changes in the inner vestibule indicative of an opening of the inner vestibule. Predictions from this model (e.g. the preferential accumulation of SERTT81A in the inward conformation, its reduced turnover number, and a larger distance between its N and C termini) were verified. Most importantly, SERTT81A (and the homologous mutations in noradrenaline and dopamine) failed to support amphetamine-induced efflux, and this was not remedied by aspartate at this position. Amphetamine-induced currents through SERTT81A were comparable with those through the wild type transporter. Both abundant Na+ entry and accumulation of SERTT81A in the inward facing conformation ought to favor amphetamine-induced efflux. Thus, we surmised that the N terminus must play a direct role in driving the transporter into a state that supports amphetamine-induced efflux. This hypothesis was verified by truncating the first 64 amino acids and by tethering the N terminus to an additional transmembrane helix. Either modification abolished amphetamine-induced efflux. We therefore conclude that the N terminus of monoamine transporters acts as a lever that sustains reverse transport.
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Affiliation(s)
- Sonja Sucic
- Center of Biomolecular Medicine and Pharmacology, Institute of Pharmacology, Medical University Vienna, A-1090 Vienna, Austria
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Gsandtner I, Keuerleber S, Thurner P, Kudlacek O. A2A adenosine receptor interacting partners (interactome). BMC Pharmacol 2009. [PMCID: PMC2778903 DOI: 10.1186/1471-2210-9-s2-a32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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49
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El-Kasaby A, Kudlacek O. Importance of the carboxyl terminus for folding and trafficking of the serotonin transporter. BMC Pharmacol 2009. [PMCID: PMC2778897 DOI: 10.1186/1471-2210-9-s2-a27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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50
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Sucic S, Dallinger S, Zdrazil B, Kudlacek O, Sandtner W, Ecker GF, Freissmuth M, Sitte HH. Mutations in the amino-terminus impair amphetamine-induced efflux by inducing inward-facing conformations of the serotonin transporter. BMC Pharmacol 2009. [PMCID: PMC2778881 DOI: 10.1186/1471-2210-9-s2-a12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
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