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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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52
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Spork M, Sohail MI, Schmid D, Ecker GF, Freissmuth M, Chiba P, Stockner T. Folding correction of ABC-transporter ABCB1 by pharmacological chaperones: a mechanistic concept. Pharmacol Res Perspect 2017; 5:e00325. [PMID: 28603639 PMCID: PMC5464349 DOI: 10.1002/prp2.325] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 03/21/2017] [Indexed: 12/20/2022] Open
Abstract
Point mutations of ATP‐binding cassette (ABC) proteins are a common cause of human diseases. Available crystal structures indicate a similarity in the architecture of several members of this protein family. Their molecular architecture makes these proteins vulnerable to mutation, when critical structural elements are affected. The latter preferentially involve the two transmembrane domain (TMD)/nucleotide‐binding domain (NBD) interfaces (transmission interfaces), formation of which requires engagement of coupling helices of intracellular loops with NBDs. Both, formation of the active sites and engagement of the coupling helices, are contingent on correct positioning of ICLs 2 and 4 and thus an important prerequisite for proper folding. Here, we show that active site compounds are capable of rescuing P‐glycoprotein (P‐gp) mutants ∆Y490 and ∆Y1133 in a concentration‐dependent manner. These trafficking deficient mutations are located at the transmission interface in pseudosymmetric position to each other. In addition, the ability of propafenone analogs to correct folding correlates with their ability to inhibit transport of model substrates. This finding indicates that folding correction and transport inhibition by propafenone analogs are brought about by binding to the active sites. Furthermore, this study demonstrates an asymmetry in folding correction with cis‐flupentixol, which reflects the asymmetric binding properties of this modulator to P‐gp. Our results suggest a mechanistic model for corrector action in a model ABC transporter based on insights into the molecular architecture of these transporters.
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Affiliation(s)
- Matthias Spork
- Institute of Medical Chemistry Center of Pathobiochemistry and Genetics Medical University of Vienna Waehringerstrasse 10 Vienna A-1090 Austria
| | - Muhammad Imran Sohail
- Institute of Medical Chemistry Center of Pathobiochemistry and Genetics Medical University of Vienna Waehringerstrasse 10 Vienna A-1090 Austria.,Department of Zoology Government College University Lahore Katchery Road Lahore 54000 Pakistan
| | - Diethart Schmid
- Institute of Physiology Center of Physiology und Pharmacology Medical University of Vienna Schwarzspanierstrasse 17 Vienna A -1090 Austria
| | - Gerhard F Ecker
- Department of Medicinal Chemistry University of Vienna Emerging Field Pharmacoinformatics Althanstrasse 14 Vienna A-1090 Austria (GFE)
| | - Michael Freissmuth
- Institute of Pharmacology Center of Physiology und Pharmacology Medical University of Vienna Waehringerstrasse 13a Vienna A-1090 Austria
| | - Peter Chiba
- Institute of Medical Chemistry Center of Pathobiochemistry and Genetics Medical University of Vienna Waehringerstrasse 10 Vienna A-1090 Austria
| | - Thomas Stockner
- Institute of Pharmacology Center of Physiology und Pharmacology Medical University of Vienna Waehringerstrasse 13a Vienna A-1090 Austria
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53
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Li Y, Mayer FP, Hasenhuetl PS, Burtscher V, Schicker K, Sitte HH, Freissmuth M, Sandtner W. Occupancy of the zinc-binding site by transition metals decreases the substrate affinity of the human dopamine transporter by an allosteric mechanism. J Biol Chem 2017; 292:7161. [PMID: 28455408 PMCID: PMC5409482 DOI: 10.1074/jbc.a116.760140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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54
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Kern C, Erdem FA, El-Kasaby A, Sandtner W, Freissmuth M, Sucic S. The N Terminus Specifies the Switch between Transport Modes of the Human Serotonin Transporter. J Biol Chem 2017; 292:3603-3613. [PMID: 28104804 PMCID: PMC5339746 DOI: 10.1074/jbc.m116.771360] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 01/18/2017] [Indexed: 10/25/2022] Open
Abstract
The serotonin transporter (SERT) and other monoamine transporters operate in either a forward transport mode where the transporter undergoes a full transport cycle or an exchange mode where the transporter seesaws through half-cycles. Amphetamines trigger the exchange mode, leading to substrate efflux. This efflux was proposed to rely on the N terminus, which was suggested to adopt different conformations in the inward facing, outward facing and amphetamine-bound states. This prediction was verified by tryptic digestion of SERT-expressing membranes: in the absence of Na+, the N terminus was rapidly digested. Amphetamine conferred protection against cleavage, suggesting a relay between the conformational states of the hydrophobic core and the N terminus. We searched for a candidate segment that supported the conformational switch by serial truncation removing 22 (ΔN22), 32 (ΔN32), or 42 (ΔN42) N-terminal residues. This did not affect surface expression, inhibitor binding, and substrate influx. However, amphetamine-induced efflux by SERT-ΔN32 or SERT-ΔN42 (but not by SERT-ΔN22) was markedly diminished. We examined the individual steps in the transport cycle by recording transporter-associated currents: the recovery rate of capacitive peak, but not of steady state, currents was significantly lower for SERT-ΔN32 than that of wild type SERT and SERT-ΔN22. Thus, the exchange mode of SERT-ΔN32 was selectively impaired. Our observations show that the N terminus affords the switch between transport modes. The findings are consistent with a model where the N terminus acts as a lever to support amphetamine-induced efflux by SERT.
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Affiliation(s)
- Carina Kern
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Fatma Asli Erdem
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Ali El-Kasaby
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Walter Sandtner
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Michael Freissmuth
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Sonja Sucic
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
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55
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Li Y, Mayer FP, Hasenhuetl PS, Burtscher V, Schicker K, Sitte HH, Freissmuth M, Sandtner W. Occupancy of the Zinc-binding Site by Transition Metals Decreases the Substrate Affinity of the Human Dopamine Transporter by an Allosteric Mechanism. J Biol Chem 2017; 292:4235-4243. [PMID: 28096460 PMCID: PMC5354487 DOI: 10.1074/jbc.m116.760140] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [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: 09/23/2016] [Revised: 12/16/2016] [Indexed: 11/06/2022] Open
Abstract
The human dopamine transporter (DAT) has a tetrahedral Zn2+-binding site. Zn2+-binding sites are also recognized by other first-row transition metals. Excessive accumulation of manganese or of copper can lead to parkinsonism because of dopamine deficiency. Accordingly, we examined the effect of Mn2+, Co2+, Ni2+, and Cu2+ on transport-associated currents through DAT and DAT-H193K, a mutant with a disrupted Zn2+-binding site. All transition metals except Mn2+ modulated the transport cycle of wild-type DAT with affinities in the low micromolar range. In this concentration range, they were devoid of any action on DAT-H193K. The active transition metals reduced the affinity of DAT for dopamine. The affinity shift was most pronounced for Cu2+, followed by Ni2+ and Zn2+ (= Co2+). The extent of the affinity shift and the reciprocal effect of substrate on metal affinity accounted for the different modes of action: Ni2+ and Cu2+ uniformly stimulated and inhibited, respectively, the substrate-induced steady-state currents through DAT. In contrast, Zn2+ elicited biphasic effects on transport, i.e. stimulation at 1 μm and inhibition at 10 μm. A kinetic model that posited preferential binding of transition metal ions to the outward-facing apo state of DAT and a reciprocal interaction of dopamine and transition metals recapitulated all experimental findings. Allosteric activation of DAT via the Zn2+-binding site may be of interest to restore transport in loss-of-function mutants.
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Affiliation(s)
- Yang Li
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria
| | - Felix P Mayer
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria
| | - Peter S Hasenhuetl
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria
| | - Verena Burtscher
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria
| | - Klaus Schicker
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria
| | - Harald H Sitte
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria
| | - Michael Freissmuth
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria
| | - Walter Sandtner
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University Vienna, Waehringerstrasse 13a, 1090 Vienna, Austria
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Abstract
The human genome encodes 19 genes of the solute carrier 6 (SLC6) family; non-synonymous changes in the coding sequence give rise to mutated transporters, which are misfolded and thus cause diseases in the affected individuals. Prominent examples include mutations in the transporters for dopamine (DAT, SLC6A3), for creatine (CT1, SLC6A8), and for glycine (GlyT2, SLC6A5), which result in infantile dystonia, mental retardation, and hyperekplexia, respectively. Thus, there is an obvious unmet medical need to identify compounds, which can remedy the folding deficit. The pharmacological correction of folding defects was originally explored in mutants of the serotonin transporter (SERT, SLC6A4), which were created to study the COPII-dependent export from the endoplasmic reticulum. This led to the serendipitous discovery of the pharmacochaperoning action of ibogaine. Ibogaine and its metabolite noribogaine also rescue several disease-relevant mutants of DAT. Because the pharmacology of DAT and SERT is exceptionally rich, it is not surprising that additional compounds have been identified, which rescue folding-deficient mutants. These compounds are not only of interest for restoring DAT function in the affected children. They are also likely to serve as useful tools to interrogate the folding trajectory of the transporter. This is likely to initiate a virtuous cycle: if the principles underlying folding of SLC6 transporters are understood, the design of pharmacochaperones ought to be facilitated.
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Affiliation(s)
- Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria.
| | - Thomas Stockner
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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57
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Sucic S, Kasture A, Mazhar Asjad HM, Kern C, El-Kasaby A, Freissmuth M. When transporters fail to be transported: how to rescue folding-deficient SLC6 transporters. ACTA ACUST UNITED AC 2016; 1:34-40. [PMID: 28405636 PMCID: PMC5386142 DOI: 10.29245/2572.942x/2016/9.1098] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [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: 12/25/2022]
Abstract
The human dopamine transporter (hDAT) belongs to the solute carrier 6 (SLC6) gene family. Point mutations in hDAT (SLC6A3) have been linked to a syndrome of dopamine transporter deficiency or infantile dystonia/parkinsonism. The mutations impair DAT folding, causing retention of variant DATs in the endoplasmic reticulum and subsequently impair transport activity. The folding trajectory of DAT itself is not understood, though many insights have been gained from studies of folding-deficient mutants of the closely related serotonin transporter (SERT); i.e. their functional rescue by pharmacochaperoning with (nor)ibogaine or heat-shock protein inhibitors. We recently provided a proof-of-principle that folding-deficits in DAT are amenable to rescue in vitro and in vivo. As a model we used the Drosophila melanogaster DAT mutant dDAT-G108Q, which phenocopies the fumin/sleepless DAT-knockout. Treatment with noribogaine and/or HSP70 inhibitor pifithrin-μ restored folding of, and dopamine transport by, dDAT-G108Q, its axonal delivery and normal sleep time in mutant flies. The possibility of functional rescue of misfolded DATs in living flies by pharmacochaperoning grants new therapeutic prospects in the remedy of folding diseases, not only in hDAT, but also in other SLC6 transporters, in particular mutants of the creatine transporter-1, which give rise to X-linked mental retardation.
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Affiliation(s)
- Sonja Sucic
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Ameya Kasture
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - H M Mazhar Asjad
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Carina Kern
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Ali El-Kasaby
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
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58
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Sohail A, Jayaraman K, Venkatesan S, Gotfryd K, Daerr M, Gether U, Loland CJ, Wanner KT, Freissmuth M, Sitte HH, Sandtner W, Stockner T. The Environment Shapes the Inner Vestibule of LeuT. PLoS Comput Biol 2016; 12:e1005197. [PMID: 27835643 PMCID: PMC5105988 DOI: 10.1371/journal.pcbi.1005197] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [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: 06/26/2016] [Accepted: 10/12/2016] [Indexed: 12/27/2022] Open
Abstract
Human neurotransmitter transporters are found in the nervous system terminating synaptic signals by rapid removal of neurotransmitter molecules from the synaptic cleft. The homologous transporter LeuT, found in Aquifex aeolicus, was crystallized in different conformations. Here, we investigated the inward-open state of LeuT. We compared LeuT in membranes and micelles using molecular dynamics simulations and lanthanide-based resonance energy transfer (LRET). Simulations of micelle-solubilized LeuT revealed a stable and widely open inward-facing conformation. However, this conformation was unstable in a membrane environment. The helix dipole and the charged amino acid of the first transmembrane helix (TM1A) partitioned out of the hydrophobic membrane core. Free energy calculations showed that movement of TM1A by 0.30 nm was driven by a free energy difference of ~15 kJ/mol. Distance measurements by LRET showed TM1A movements, consistent with the simulations, confirming a substantially different inward-open conformation in lipid bilayer from that inferred from the crystal structure. Crystal structures of the bacterial small amino acid transporter LeuT provided structural evidence for the alternating access model. Thereby, these structures shaped our understanding of the mechanisms underlying substrate translocation by neurotransmitter transporters. However, it has been questioned, if the crystallized inward-open conformation of LeuT can exist in the membrane environment. Here we show that, while stable in detergent micelles, the inward-open conformation of LeuT is of high energy and undergoes structural readjustments. We use a multi-faceted approach including molecular dynamics simulations, scintillation proximity assays, free energy calculations and apply for the first time lanthanide resonance energy transfer measurements to verify the in silico predictions. In silico and in vitro approaches using the same conditions allowed us to combine the macroscopic experimental data with microscopic all atom results from simulations to identify the underlying driving forces: partitioning of charged and polar groups from the hydrophobic membrane interior to the hydrophilic environment. We propose that the inward-facing state shows a much smaller movement of TM1A, but large enough to create an access path to the S1 substrate binding site from the vestibule.
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Affiliation(s)
- Azmat Sohail
- Medical University of Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Vienna, Austria
| | - Kumaresan Jayaraman
- Medical University of Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Vienna, Austria
| | - Santhoshkannan Venkatesan
- Medical University of Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Vienna, Austria
| | - Kamil Gotfryd
- University of Copenhagen, Faculty of Health and Medical Sciences Denmark, Department of Neuroscience and Pharmacology, Copenhagen, Denmark
- University of Copenhagen, Faculty of Health Sciences Denmark, Department of Biomedical Sciences, Copenhagen, Denmark
| | - Markus Daerr
- Ludwig Maximilians University Munich, Department of Pharmacy, Center of Drug Research, Munich, Germany
| | - Ulrik Gether
- University of Copenhagen, Faculty of Health and Medical Sciences Denmark, Department of Neuroscience and Pharmacology, Copenhagen, Denmark
| | - Claus J. Loland
- University of Copenhagen, Faculty of Health and Medical Sciences Denmark, Department of Neuroscience and Pharmacology, Copenhagen, Denmark
| | - Klaus T. Wanner
- Ludwig Maximilians University Munich, Department of Pharmacy, Center of Drug Research, Munich, Germany
| | - Michael Freissmuth
- Medical University of Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Vienna, Austria
| | - Harald H. Sitte
- Medical University of Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Vienna, Austria
- * E-mail:
| | - Walter Sandtner
- Medical University of Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Vienna, Austria
| | - Thomas Stockner
- Medical University of Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Vienna, Austria
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59
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Schaletzki Y, Kromrey ML, Bröderdorf S, Hammer E, Grube M, Hagen P, Sucic S, Freissmuth M, Völker U, Greinacher A, Rauch BH, Kroemer HK, Jedlitschky G. Several adaptor proteins promote intracellular localisation of the transporter MRP4/ABCC4 in platelets and haematopoietic cells. Thromb Haemost 2016; 117:105-115. [PMID: 27761583 DOI: 10.1160/th16-01-0045] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 09/20/2016] [Indexed: 12/29/2022]
Abstract
The multidrug resistance protein 4 (MRP4/ABCC4) has been identified as an important transporter for signalling molecules including cyclic nucleotides and several lipid mediators in platelets and may thus represent a novel target to interfere with platelet function. Besides its localisation in the plasma membrane, MRP4 has been also detected in the membrane of dense granules in resting platelets. In polarised cells it is localised at the basolateral or apical plasma membrane. To date, the mechanism of MRP4 trafficking has not been elucidated; protein interactions may regulate both the localisation and function of this transporter. We approached this issue by searching for interacting proteins by in vitro binding assays, followed by immunoblotting and mass spectrometry, and by visualising their co-localisation in platelets and haematopoietic cells. We identified the PDZ domain containing scaffold proteins ezrin-binding protein 50 (EBP50/NHERF1), postsynaptic density protein 95 (PSD95), and sorting nexin 27 (SNX27), but also the adaptor protein complex 3 subunit β3A (AP3B1) and the heat shock protein HSP90 as putative interaction partners of MRP4. The knock-down of SNX27, PSD95, and AP3B1 by siRNA in megakaryoblastic leukaemia cells led to a redistribution of MRP4 from intracellular structures to the plasma membrane. Inhibition of HSP90 led to a diminished expression and retention of MRP4 in the endoplasmic reticulum. These results indicate that MRP4 localisation and function are regulated by multiple protein interactions. Changes in the adaptor proteins can hence lead to altered localisation and function of the transporter.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | - Gabriele Jedlitschky
- Gabriele Jedlitschky PhD, Department of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Felix-Hausdorff-Str. 3, 17487 Greifswald, Germany, Tel.: +49 3834 8622146, Fax: +49 3834 865631, E-mail:
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60
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Hasenhuetl PS, Freissmuth M, Sandtner W. Electrogenic Binding of Intracellular Cations Defines a Kinetic Decision Point in the Transport Cycle of the Human Serotonin Transporter. J Biol Chem 2016; 291:25864-25876. [PMID: 27756841 PMCID: PMC5207061 DOI: 10.1074/jbc.m116.753319] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [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] [Received: 08/11/2016] [Revised: 10/13/2016] [Indexed: 12/02/2022] Open
Abstract
The plasmalemmal monoamine transporters clear the extracellular space from their cognate substrates and sustain cellular monoamine stores even during neuronal activity. In some instances, however, the transporters enter a substrate-exchange mode, which results in release of intracellular substrate. Understanding what determines the switch between these two transport modes demands time-resolved measurements of intracellular (co-)substrate binding and release. Here, we report an electrophysiological investigation of intracellular solute-binding to the human serotonin transporter (SERT) expressed in HEK-293 cells. We measured currents induced by rapid application of serotonin employing varying intracellular (co-)substrate concentrations and interpreted the data using kinetic modeling. Our measurements revealed that the induction of the substrate-exchange mode depends on both voltage and intracellular Na+ concentrations because intracellular Na+ release occurs before serotonin release and is highly electrogenic. This voltage dependence was blunted by electrogenic binding of intracellular K+ and, notably, also H+. In addition, our data suggest that Cl− is bound to SERT during the entire catalytic cycle. Our experiments, therefore, document an essential role of electrogenic binding of K+ or of H+ to the inward-facing conformation of SERT in (i) cancelling out the electrogenic nature of intracellular Na+ release and (ii) in selecting the forward-transport over the substrate-exchange mode. Finally, the kinetics of intracellular Na+ release and K+ (or H+) binding result in a voltage-independent rate-limiting step where SERT may return to the outward-facing state in a KCl- or HCl-bound form.
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Affiliation(s)
- Peter S Hasenhuetl
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University Vienna, Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
| | - Michael Freissmuth
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University Vienna, Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
| | - Walter Sandtner
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University Vienna, Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
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61
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Kollmann K, Heller G, Schneckenleithner C, Warsch W, Scheicher R, Ott RG, Schäfer M, Fajmann S, Schlederer M, Schiefer AI, Reichart U, Mayerhofer M, Hoeller C, Zöchbauer-Müller S, Kerjaschki D, Bock C, Kenner L, Hoefler G, Freissmuth M, Green AR, Moriggl R, Busslinger M, Malumbres M, Sexl V. A Kinase-Independent Function of CDK6 Links the Cell Cycle to Tumor Angiogenesis. Cancer Cell 2016; 30:359-360. [PMID: 27505678 PMCID: PMC5637299 DOI: 10.1016/j.ccell.2016.07.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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62
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Kasture A, El-Kasaby A, Szöllősi D, Asjad HMM, Grimm A, Stockner T, Hummel T, Freissmuth M, Sucic S. Functional Rescue of a Misfolded Drosophila melanogaster Dopamine Transporter Mutant Associated with a Sleepless Phenotype by Pharmacological Chaperones. J Biol Chem 2016; 291:20876-20890. [PMID: 27481941 PMCID: PMC5076501 DOI: 10.1074/jbc.m116.737551] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 07/13/2016] [Indexed: 12/15/2022] Open
Abstract
Folding-defective mutants of the human dopamine transporter (DAT) cause a syndrome of infantile dystonia/parkinsonism. Here, we provide a proof-of-principle that the folding deficit is amenable to correction in vivo by two means, the cognate DAT ligand noribogaine and the HSP70 inhibitor, pifithrin-μ. We examined the Drosophila melanogaster (d) mutant dDAT-G108Q, which leads to a sleepless phenotype in flies harboring this mutation. Molecular dynamics simulations suggested an unstable structure of dDAT-G108Q consistent with a folding defect. This conjecture was verified; heterologously expressed dDAT-G108Q and the human (h) equivalent hDAT-G140Q were retained in the endoplasmic reticulum in a complex with endogenous folding sensors (calnexin and HSP70-1A). Incubation of the cells with noribogaine (a DAT ligand selective for the inward-facing state) and/or pifithrin-μ (an HSP70 inhibitor) restored folding of, and hence dopamine transport by, dDAT-G108Q and hDAT-G140Q. The mutated versions of DAT were confined to the cell bodies of the dopaminergic neurons in the fly brain and failed to reach the axonal compartments. Axonal delivery was restored, and sleep time was increased to normal length (from 300 to 1000 min/day) if the dDAT-G108Q-expressing flies were treated with noribogaine and/or pifithrin-μ. Rescuing misfolded versions of DAT by pharmacochaperoning is of therapeutic interest; it may provide opportunities to remedy disorders arising from folding-defective mutants of human DAT and of other related SLC6 transporters.
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Affiliation(s)
- Ameya Kasture
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Ali El-Kasaby
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria.,the Department of Pharmacology, Faculty of Veterinary Medicine, Mansoura University, 35516 Mansoura, Egypt, and
| | - Daniel Szöllősi
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - H M Mazhar Asjad
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Alexandra Grimm
- the Department of Neurobiology, University of Vienna, A-1090 Vienna, Austria
| | - Thomas Stockner
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Thomas Hummel
- the Department of Neurobiology, University of Vienna, A-1090 Vienna, Austria
| | - Michael Freissmuth
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria,
| | - Sonja Sucic
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
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63
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Nasrollahi-Shirazi S, Sucic S, Yang Q, Freissmuth M, Nanoff C. Comparison of the β-Adrenergic Receptor Antagonists Landiolol and Esmolol: Receptor Selectivity, Partial Agonism, and Pharmacochaperoning Actions. J Pharmacol Exp Ther 2016; 359:73-81. [PMID: 27451411 DOI: 10.1124/jpet.116.232884] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 07/18/2016] [Indexed: 01/08/2023] Open
Abstract
Blockage of β1-adrenergic receptors is one of the most effective treatments in cardiovascular medicine. Esmolol was introduced some three decades ago as a short-acting β1-selective antagonist. Landiolol is a more recent addition. Here we compared the two compounds for their selectivity for β1-adrenergic receptors over β2-adrenergic receptors, partial agonistic activity, signaling bias, and pharmacochaperoning action by using human embryonic kidney (HEK)293 cell lines, which heterologously express each human receptor subtype. The affinity of landiolol for β1-adrenergic receptors and β2-adrenergic receptors was higher and lower than that of esmolol, respectively, resulting in an improved selectivity (216-fold versus 30-fold). The principal metabolite of landiolol (M1) was also β1-selective, but its affinity was very low. Both landiolol and esmolol caused a very modest rise in cAMP levels but a robust increase in the phosphorylation of extracellular signal regulated kinases 1 and 2, indicating that the two drugs exerted partial agonist activity with a signaling bias. If cells were incubated for ≥24 hours in the presence of ≥1 μM esmolol, the levels of β1-adrenergic-but not of β2-adrenergic-receptors increased. This effect was contingent on export of the β1-receptor from endoplasmic reticulum and was not seen in the presence of landiolol. On the basis of these observations, we conclude that landiolol offers the advantage of: 1) improved selectivity and 2) the absence of pharmacochaperoning activity, which sensitizes cells to rebound effects upon drug discontinuation.
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Affiliation(s)
- Shahrooz Nasrollahi-Shirazi
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Qiong Yang
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Christian Nanoff
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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64
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Kazemi Z, Bergmayr C, Prchal-Murphy M, Javaheri T, Themanns M, Pham HTT, Strohmaier W, Sexl V, Freissmuth M, Zebedin-Brandl E. Repurposing Treprostinil for Enhancing Hematopoietic Progenitor Cell Transplantation. Mol Pharmacol 2016; 89:630-44. [PMID: 26989084 PMCID: PMC4885501 DOI: 10.1124/mol.116.103267] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 03/14/2016] [Indexed: 12/23/2022] Open
Abstract
Activation of Gs-coupled receptors enhances engraftment of hematopoietic stem and progenitor cells (HSPCs). We tested the hypothesis that treprostinil, a prostacyclin analog approved for the treatment of pulmonary hypertension, can be repurposed to improve hematopoietic stem cell transplantation. Murine and human HSPCs were isolated from bone marrow and umbilical cord blood, respectively. Prostanoid receptor agonists and the combination thereof with forskolin were tested for their capacity to stimulate [3H]cAMP accumulation in HSPCs. Three independent approaches were employed to verify the ability of agonist-activated HSPCs to reconstitute the bone marrow in lethally irradiated recipient mice. The underlying mechanism was explored in cellular migration assays and by blocking C-X-C motif chemokine receptor 4 (CXCR4). Among several prostanoid agonists tested in combination with forskolin, treprostinil was most efficacious in raising intracellular cAMP levels in murine and human HPSCs. Injection of murine and human HSPCs, which had been pretreated with treprostinil and forskolin, enhanced survival of lethally irradiated recipient mice. Survival was further improved if recipient mice were subcutaneously administered treprostinil (0.15 mg kg−1 8 h−1) for 10 days. This regimen also reduced the number of HSPCs required to rescue lethally irradiated mice. Enhanced survival of recipient mice was causally related to treprostinil-enhanced CXCR4-dependent migration of HSPCs. Treprostinil stimulates the engraftment of human and murine hematopoietic stem cells without impairing their capacity for self-renewal. The investigated dose range corresponds to the dose approved for human use. Hence, these findings may be readily translated into a clinical application.
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Affiliation(s)
- Zahra Kazemi
- Institute of Pharmacology, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (Z.K., C.B., M.T., M.F., E.Z.-B.); Institute of Pharmacology and Toxicology, University of Veterinary Medicine, Vienna, Austria (M.P.-M., V.S.); Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria (T.J., H.T.T.P.); SciPharm SàRL, L-2540 Luxembourg (W.S.)
| | - Christian Bergmayr
- Institute of Pharmacology, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (Z.K., C.B., M.T., M.F., E.Z.-B.); Institute of Pharmacology and Toxicology, University of Veterinary Medicine, Vienna, Austria (M.P.-M., V.S.); Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria (T.J., H.T.T.P.); SciPharm SàRL, L-2540 Luxembourg (W.S.)
| | - Michaela Prchal-Murphy
- Institute of Pharmacology, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (Z.K., C.B., M.T., M.F., E.Z.-B.); Institute of Pharmacology and Toxicology, University of Veterinary Medicine, Vienna, Austria (M.P.-M., V.S.); Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria (T.J., H.T.T.P.); SciPharm SàRL, L-2540 Luxembourg (W.S.)
| | - Tahereh Javaheri
- Institute of Pharmacology, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (Z.K., C.B., M.T., M.F., E.Z.-B.); Institute of Pharmacology and Toxicology, University of Veterinary Medicine, Vienna, Austria (M.P.-M., V.S.); Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria (T.J., H.T.T.P.); SciPharm SàRL, L-2540 Luxembourg (W.S.)
| | - Madeleine Themanns
- Institute of Pharmacology, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (Z.K., C.B., M.T., M.F., E.Z.-B.); Institute of Pharmacology and Toxicology, University of Veterinary Medicine, Vienna, Austria (M.P.-M., V.S.); Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria (T.J., H.T.T.P.); SciPharm SàRL, L-2540 Luxembourg (W.S.)
| | - Ha T T Pham
- Institute of Pharmacology, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (Z.K., C.B., M.T., M.F., E.Z.-B.); Institute of Pharmacology and Toxicology, University of Veterinary Medicine, Vienna, Austria (M.P.-M., V.S.); Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria (T.J., H.T.T.P.); SciPharm SàRL, L-2540 Luxembourg (W.S.)
| | - Wolfgang Strohmaier
- Institute of Pharmacology, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (Z.K., C.B., M.T., M.F., E.Z.-B.); Institute of Pharmacology and Toxicology, University of Veterinary Medicine, Vienna, Austria (M.P.-M., V.S.); Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria (T.J., H.T.T.P.); SciPharm SàRL, L-2540 Luxembourg (W.S.)
| | - Veronika Sexl
- Institute of Pharmacology, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (Z.K., C.B., M.T., M.F., E.Z.-B.); Institute of Pharmacology and Toxicology, University of Veterinary Medicine, Vienna, Austria (M.P.-M., V.S.); Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria (T.J., H.T.T.P.); SciPharm SàRL, L-2540 Luxembourg (W.S.)
| | - Michael Freissmuth
- Institute of Pharmacology, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (Z.K., C.B., M.T., M.F., E.Z.-B.); Institute of Pharmacology and Toxicology, University of Veterinary Medicine, Vienna, Austria (M.P.-M., V.S.); Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria (T.J., H.T.T.P.); SciPharm SàRL, L-2540 Luxembourg (W.S.)
| | - Eva Zebedin-Brandl
- Institute of Pharmacology, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (Z.K., C.B., M.T., M.F., E.Z.-B.); Institute of Pharmacology and Toxicology, University of Veterinary Medicine, Vienna, Austria (M.P.-M., V.S.); Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria (T.J., H.T.T.P.); SciPharm SàRL, L-2540 Luxembourg (W.S.)
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65
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Zhu R, Heilinger A, Newman AH, Freissmuth M, Sitte HH, Hinterdorfer P. Nanopharmacological Force Sensing Reveals Two Ligand Binding Sites in Monoamine Transporters. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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66
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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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67
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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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68
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Schmid D, Koenig X, Bulusu S, Schicker K, Freissmuth M, Sitte HH, Sandtner W. The conservative view: is it necessary to implant a stent into the dopamine transporter? Br J Pharmacol 2015; 172:4775-8. [PMID: 24824446 PMCID: PMC4561504 DOI: 10.1111/bph.12766] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 04/01/2014] [Accepted: 04/15/2014] [Indexed: 11/30/2022] Open
Abstract
This article is a reply to De Felice LJ and Cameron KN (2015). Comments on ‘A quantitative model of amphetamine action on the serotonin transporter’, by Sandtner et al., Br J Pharmacol 171: 1007–1018. Br J Pharmacol 172: this issue, doi: 10.1111/bph.12767, commenting on Sandtner W, Schmid D, Schicker K, Gerstbrein K, Koenig X, Mayer FP, Boehm S, Freissmuth M and Sitte HH (2014). A quantitative model of amphetamine action on the 5-HT transporter. Br J Pharmacol 171: 1007–1018. doi: 10.1111/bph.12520
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Affiliation(s)
- D Schmid
- Center of Physiology and Pharmacology, Medical University Vienna, Vienna, Austria
| | - X Koenig
- Center of Physiology and Pharmacology, Medical University Vienna, Vienna, Austria
| | - S Bulusu
- Center of Physiology and Pharmacology, Medical University Vienna, Vienna, Austria
| | - K Schicker
- Center of Physiology and Pharmacology, Medical University Vienna, Vienna, Austria
| | - M Freissmuth
- Center of Physiology and Pharmacology, Medical University Vienna, Vienna, Austria
| | - H H Sitte
- Center of Physiology and Pharmacology, Medical University Vienna, Vienna, Austria
| | - W Sandtner
- Center of Physiology and Pharmacology, Medical University Vienna, Vienna, Austria
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69
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Li Y, Hasenhuetl PS, Schicker K, Sitte HH, Freissmuth M, Sandtner W. Dual Action of Zn2+ on the Transport Cycle of the Dopamine Transporter. J Biol Chem 2015; 290:31069-76. [PMID: 26504078 PMCID: PMC4692231 DOI: 10.1074/jbc.m115.688275] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [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: 08/26/2015] [Indexed: 11/21/2022] Open
Abstract
The dopamine transporter shapes dopaminergic neurotransmission by clearing extracellular dopamine and by replenishing vesicular stores. The dopamine transporter carries an endogenous binding site for Zn2+, but the nature of the Zn2+-dependent modulation has remained elusive: both, inhibition and stimulation of DAT have been reported. Here, we exploited the high time resolution of patch-clamp recordings to examine the effects of Zn2+ on the transport cycle of DAT: we recorded peak currents associated with substrate translocation and steady-state currents reflecting the forward transport mode of DAT. Zn2+ depressed the peak current but enhanced the steady-state current through DAT. The parsimonious explanation is preferential binding of Zn2+ to the outward facing conformation of DAT, which allows for an allosteric activation of DAT, in both, the forward transport mode and substrate exchange mode. We directly confirmed that Zn2+ dissociated more rapidly from the inward- than from the outward-facing state of DAT. Finally, we formulated a kinetic model for the action of Zn2+ on DAT that emulated all current experimental observations and accounted for all previous (in part contradictory) findings. Importantly, the model predicts that the intracellular Na+ concentration determines whether substrate uptake by DAT is stimulated or inhibited by Zn2+. This prediction was directly verified. The mechanistic framework provided by the current model is of relevance for the rational design of allosteric activators of DAT. These are of interest for treating de novo loss-of-function mutations of DAT associated with neuropsychiatric disorders such as attention deficit hyperactivity disorder (ADHD).
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Affiliation(s)
- Yang Li
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
| | - Peter S Hasenhuetl
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
| | - Klaus Schicker
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
| | - Harald H Sitte
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
| | - Michael Freissmuth
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
| | - Walter Sandtner
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
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70
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Venkatesan S, Saha K, Sohail A, Sandtner W, Freissmuth M, Ecker GF, Sitte HH, Stockner T. Refinement of the Central Steps of Substrate Transport by the Aspartate Transporter GltPh: Elucidating the Role of the Na2 Sodium Binding Site. PLoS Comput Biol 2015; 11:e1004551. [PMID: 26485255 PMCID: PMC4618328 DOI: 10.1371/journal.pcbi.1004551] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [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: 03/30/2015] [Accepted: 08/12/2015] [Indexed: 01/15/2023] Open
Abstract
Glutamate homeostasis in the brain is maintained by glutamate transporter mediated accumulation. Impaired transport is associated with several neurological disorders, including stroke and amyotrophic lateral sclerosis. Crystal structures of the homolog transporter GltPh from Pyrococcus horikoshii revealed large structural changes. Substrate uptake at the atomic level and the mechanism of ion gradient conversion into directional transport remained enigmatic. We observed in repeated simulations that two local structural changes regulated transport. The first change led to formation of the transient Na2 sodium binding site, triggered by side chain rotation of T308. The second change destabilized cytoplasmic ionic interactions. We found that sodium binding to the transiently formed Na2 site energized substrate uptake through reshaping of the energy hypersurface. Uptake experiments in reconstituted proteoliposomes confirmed the proposed mechanism. We reproduced the results in the human glutamate transporter EAAT3 indicating a conserved mechanics from archaea to humans. We used the archaeal homolog GltPh of the human glutamate transporters to refine our understanding how large scale conformational changes are translated into substrate translocation. We identified the structural changes that accompany substrate transport and convert the energy stored in the ion gradient into a directional transport. Insights into the mechanics of these transporters are likely to increase our understanding of how they contribute to excitotoxicity and to develop drugs, which preclude the underlying accumulation of glutamate in the synaptic cleft.
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Affiliation(s)
- SanthoshKannan Venkatesan
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Kusumika Saha
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Azmat Sohail
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Walter Sandtner
- 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
| | - Gerhard F. Ecker
- Division of Drug Design & Medicinal Chemistry, Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - Harald H. Sitte
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Thomas Stockner
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
- * E-mail:
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71
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Kong E, Sucic S, Monje FJ, Reisinger SN, Savalli G, Diao W, Khan D, Ronovsky M, Cabatic M, Koban F, Freissmuth M, Pollak DD. Corrigendum: STAT3 controls IL6-dependent regulation of serotonin transporter function and depression-like behaviour. Sci Rep 2015; 5:11965. [PMID: 26177279 PMCID: PMC4502831 DOI: 10.1038/srep11965] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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72
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Hasenhuetl PS, Schicker K, Koenig X, Li Y, Sarker S, Stockner T, Sucic S, Sitte HH, Freissmuth M, Sandtner W. Ligand Selectivity among the Dopamine and Serotonin Transporters Specified by the Forward Binding Reaction. Mol Pharmacol 2015; 88:12-8. [PMID: 25873594 DOI: 10.1124/mol.115.099036] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 04/14/2015] [Indexed: 11/08/2023] Open
Abstract
The membrane transporters for the monoamines serotonin (SERT) and dopamine (DAT) are prominent targets of various psychoactive substances, including competitive inhibitors, such as tricyclic antidepressants, methylphenidate, and cocaine. Upon rapid application of a substrate, SERT and DAT display an inwardly directed current comprised of a peak and a steady-state component. Binding of a competitive inhibitor to the transporter leads to reduction of the peak current amplitude because occupancy of the transporter by an inhibitor prevents the induction of the peak current by the substrate. We show that the inhibitory effect on the peak current can be used to study the association rate constant (k(on)), dissociation rate constant (k(off)), and equilibrium dissociation constant (K(D)) of chemically distinct SERT and DAT inhibitors, with high temporal precision and without the need of high-affinity radioligands as surrogates. We exemplify our approach by measuring the kinetics of cocaine, methylphenidate, and desipramine binding to SERT and DAT. Our analysis revealed that the selectivity of methylphenidate and desipramine for DAT and SERT, respectively, can be accounted for by their rate of association and not by the residence time in their respective binding sites.
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Affiliation(s)
- Peter S Hasenhuetl
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (P.S.H., K.S., X.K., Y.L., Su.S., T.S., So.S., H.H.S., M.F., W.S.)
| | - Klaus Schicker
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (P.S.H., K.S., X.K., Y.L., Su.S., T.S., So.S., H.H.S., M.F., W.S.)
| | - Xaver Koenig
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (P.S.H., K.S., X.K., Y.L., Su.S., T.S., So.S., H.H.S., M.F., W.S.)
| | - Yang Li
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (P.S.H., K.S., X.K., Y.L., Su.S., T.S., So.S., H.H.S., M.F., W.S.)
| | - Subhodeep Sarker
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (P.S.H., K.S., X.K., Y.L., Su.S., T.S., So.S., H.H.S., M.F., W.S.)
| | - Thomas Stockner
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (P.S.H., K.S., X.K., Y.L., Su.S., T.S., So.S., H.H.S., M.F., W.S.)
| | - Sonja Sucic
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (P.S.H., K.S., X.K., Y.L., Su.S., T.S., So.S., H.H.S., M.F., W.S.)
| | - Harald H Sitte
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (P.S.H., K.S., X.K., Y.L., Su.S., T.S., So.S., H.H.S., M.F., W.S.)
| | - Michael Freissmuth
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (P.S.H., K.S., X.K., Y.L., Su.S., T.S., So.S., H.H.S., M.F., W.S.)
| | - Walter Sandtner
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria (P.S.H., K.S., X.K., Y.L., Su.S., T.S., So.S., H.H.S., M.F., W.S.)
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73
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Koban F, El-Kasaby A, Häusler C, Stockner T, Simbrunner BM, Sitte HH, Freissmuth M, Sucic S. A salt bridge linking the first intracellular loop with the C terminus facilitates the folding of the serotonin transporter. J Biol Chem 2015; 290:13263-78. [PMID: 25869136 PMCID: PMC4505579 DOI: 10.1074/jbc.m115.641357] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [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: 01/27/2015] [Indexed: 12/13/2022] Open
Abstract
The folding trajectory of solute carrier 6 (SLC6) family members is of interest because point mutations result in misfolding and thus cause clinically relevant phenotypes in people. Here we examined the contribution of the C terminus in supporting folding of the serotonin transporter (SERT; SLC6A4). Our working hypothesis posited that the amphipathic nature of the C-terminal α-helix (Thr603–Thr613) was important for folding of SERT. Accordingly, we disrupted the hydrophobic moment of the α-helix by replacing Phe604, Ile608, or Ile612 by Gln. The bulk of the resulting mutants SERT-F604Q, SERT-I608Q, and SERT-I612Q were retained in the endoplasmic reticulum, but their residual delivery to the cell surface still depended on SEC24C. This indicates that the amphipathic nature of the C-terminal α-helix was dispensable to endoplasmic reticulum export. The folding trajectory of SERT is thought to proceed through the inward facing conformation. Consistent with this conjecture, cell surface expression of the misfolded mutants was restored by (i) introducing second site suppressor mutations, which trap SERT in the inward facing state, or (ii) by the pharmacochaperone noribogaine, which binds to the inward facing conformation. Finally, mutation of Glu615 at the end of the C-terminal α-helix to Lys reduced surface expression of SERT-E615K. A charge reversal mutation in intracellular loop 1 restored surface expression of SERT-R152E/E615K to wild type levels. These observations support a mechanistic model where the C-terminal amphipathic helix is stabilized by an intramolecular salt bridge between residues Glu615 and Arg152. This interaction acts as a pivot in the conformational search associated with folding of SERT.
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Affiliation(s)
- Florian Koban
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and
| | - Ali El-Kasaby
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and the Department of Pharmacology, Faculty of Veterinary Medicine, Mansoura University, 35516 Mansoura, Egypt
| | - Cornelia Häusler
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and
| | - Thomas Stockner
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and
| | - Benedikt M Simbrunner
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and
| | - Harald H Sitte
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and
| | - Michael Freissmuth
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and
| | - Sonja Sucic
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and
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74
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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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75
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Freissmuth M, Hasenhuetl P, Sucic S, Sitte H, Sandtner W. Association Rate Constants as Determinants of Ligand Selectivity:Lessons from The Dopamine And The Serotonin Transporter. FASEB J 2015. [DOI: 10.1096/fasebj.29.1_supplement.932.1] [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)
| | | | - Sonja Sucic
- PharmacologyMedical University of ViennaViennaAustria
| | - Harald Sitte
- PharmacologyMedical University of ViennaViennaAustria
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76
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Sucic S, El‐Kasaby A, Koban F, Freissmuth M. An Ionic Lock Between Intracellular Loop 1 and a C‐terminal Amphipathic Helix Stabilizes the Serotonin Transporter Along its Folding Trajectory. FASEB J 2015. [DOI: 10.1096/fasebj.29.1_supplement.566.11] [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)
- Sonja Sucic
- Institute of Pharmacology Medical University of ViennaViennaAustria
| | - Ali El‐Kasaby
- Institute of Pharmacology Medical University of ViennaViennaAustria
| | - Florian Koban
- Institute of Pharmacology Medical University of ViennaViennaAustria
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77
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Rudashevskaya EL, Stockner T, Trauner M, Freissmuth M, Chiba P. Pharmacological correction of misfolding of ABC proteins. Drug Discov Today Technol 2015; 12:e87-94. [PMID: 25027379 PMCID: PMC4039138 DOI: 10.1016/j.ddtec.2014.03.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The endoplasmic reticulum (ER) quality control system distinguishes between correctly and incorrectly folded proteins to prevent processing of aberrantly folded conformations along the secretory pathway. Non-synonymous mutations can lead to misfolding of ABC proteins and associated disease phenotypes. Specific phenotypes may at least partially be corrected by small molecules, so-called pharmacological chaperones. Screening for folding correctors is expected to open an avenue for treatment of diseases such as cystic fibrosis and intrahepatic cholestasis.
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Affiliation(s)
- Elena L Rudashevskaya
- Institute of Medical Chemistry, Medical University of Vienna, Waehringerstrasse 10, Vienna, Austria
| | - Thomas Stockner
- Institute of Pharmacology, Medical University of Vienna, Waehringerstrasse 13, Vienna, Austria
| | - Michael Trauner
- Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Waehringer Guertel 18-20, Austria
| | - Michael Freissmuth
- Institute of Pharmacology, Medical University of Vienna, Waehringerstrasse 13, Vienna, Austria
| | - Peter Chiba
- Institute of Medical Chemistry, Medical University of Vienna, Waehringerstrasse 10, Vienna, Austria
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78
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Sitte HH, Schütz GJ, Freissmuth M. Cooperativity between individual transporter protomers: new data fuelling old complexes. J Neurochem 2015; 133:163-6. [PMID: 25772534 DOI: 10.1111/jnc.13086] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 03/02/2015] [Indexed: 01/01/2023]
Abstract
Neurotransmitter transporters are arranged in an oligomeric quaternary structure as evidenced by crosslinking or fluorescence resonance energy transfer (FRET)-microscopy. In a study by Zhen and colleagues highlighted by this Editorial in the current issue of Journal of Neurochemistry, the combination of mutant and wild-type dopamine transporter (DAT) has been used to establish the cooperation between transporter protomers; the DAT mutant version has an altered affinity for the radiolabelled inhibitor [³H]CFT. Zhen and colleagues predict how saturation-binding curves ought to look, if the two binding sites (i.e. of the wild type and the mutant DAT) operated independently. The results are clear-cut: the experimental observations are inconsistent with curves obtained by mixing independent binding sites. Thus, by definition, the binding sites cooperate. Read the full article 'Dopamine transporter oligomerization: impact of combining protomers with differential cocaine analog binding affinities' on page 167.
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Affiliation(s)
- Harald H Sitte
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Vienna, Austria
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79
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Kong E, Sucic S, Monje FJ, Reisinger SN, Savalli G, Diao W, Khan D, Ronovsky M, Cabatic M, Koban F, Freissmuth M, Pollak DD. STAT3 controls IL6-dependent regulation of serotonin transporter function and depression-like behavior. Sci Rep 2015; 5:9009. [PMID: 25760924 PMCID: PMC5390910 DOI: 10.1038/srep09009] [Citation(s) in RCA: 67] [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: 09/23/2014] [Accepted: 02/11/2015] [Indexed: 12/22/2022] Open
Abstract
Experimental evidence suggests a role for the immune system in the pathophysiology of depression. A specific involvement of the proinflammatory cytokine interleukin 6 (IL6) in both, patients suffering from the disease and pertinent animal models, has been proposed. However, it is not clear how IL6 impinges on neurotransmission and thus contributes to depression. Here we tested the hypothesis that IL6-induced modulation of serotonergic neurotransmission through the STAT3 signaling pathway contributes to the role of IL6 in depression. Addition of IL6 to JAR cells, endogenously expressing SERT, reduced SERT activity and downregulated SERT mRNA and protein levels. Similarly, SERT expression was reduced upon IL6 treatment in the mouse hippocampus. Conversely, hippocampal tissue of IL6-KO mice contained elevated levels of SERT and IL6-KO mice displayed a reduction in depression-like behavior and blunted response to acute antidepressant treatment. STAT3 IL6-dependently associated with the SERT promoter and inhibition of STAT3 blocked the effect of IL6 in-vitro and modulated depression-like behavior in-vivo. These observations demonstrate that IL6 directly controls SERT levels and consequently serotonin reuptake and identify STAT3-dependent regulation of SERT as conceivable neurobiological substrate for the involvement of IL6 in depression.
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Affiliation(s)
- Eryan Kong
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna
| | - Sonja Sucic
- Department of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna
| | - Francisco J. Monje
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna
| | - Sonali N. Reisinger
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna
| | - Giorgia Savalli
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna
| | - Weifei Diao
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna
| | - Deeba Khan
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna
| | - Marianne Ronovsky
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna
| | - Maureen Cabatic
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna
| | - Florian Koban
- Department of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna
| | - Michael Freissmuth
- Department of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna
| | - Daniela D. Pollak
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna
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80
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Promberger R, Ott J, Bures C, Freissmuth M, Seemann R, Hermann M. Perioperative kinetics of parathyroid hormone in unilateral, primary thyroid surgery. Endocrine 2015; 48:293-8. [PMID: 24858628 DOI: 10.1007/s12020-014-0300-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Accepted: 05/09/2014] [Indexed: 02/01/2023]
Abstract
Dysfunction of the parathyroid glands is an important cause of complications after thyroid surgery. Intraoperative monitoring of the function of the parathyroid glands can be performed using parathyroid hormone (PTH) kinetics. Unilateral thyroid surgery is associated with a decreased risk for postoperative hypocalcemia (POH) and permanent hypoparathyroidism (PEH). We focused on unilateral thyroid surgery by monitoring the functionality of the parathyroid glands and comparing the perioperative PTH kinetics of patients with and without POH. In a prospective study, 143 patients scheduled for unilateral thyroid surgery underwent monitoring of perioperative changes in serum PTH and serum calcium levels, and of clinical symptoms of hypocalcemia. The rates of POH and PEH were 18.2 and 0%, respectively. In patients without POH, PTH significantly increased from the time of skin incision to the end of the operation and after the operation (20.1 pg/ml, IQR 15.5-26.8 vs. 21.4 pg/ml, IQR 16.4-29.5; p=0.005), which was not the case in patients who developed POH. In a multivariate analysis of predictive factors for POH, two parameters became significant, namely female gender (odds ratio 6.87, 95% confidence interval 0.92-51.01) and lower initial serum calcium levels (odds ratio 3.54*e(-8), 95% confidence interval 3.63*e(-12); 0.00). The rate of POH was unexpectedly high. Rather than intraoperative PTH declines, an unstable balance of factors that influence calcium metabolism likely is the major contributor to POH after unilateral thyroid surgery. There was no case of PEH after unilateral, primary thyroid surgery, which underlines the need for an individualized approach to the extent of resection.
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Affiliation(s)
- Regina Promberger
- Second Department of Surgery "Kaiserin Elisabeth", Krankenanstalt Rudolfstiftung, Juchgasse 25, 1030, Vienna, Austria
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81
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Hasenhuetl PS, Freissmuth M, Sitte HH, Sandtner W. A Kinetic Assessment of Ligand Binding to Monoamine-Transporters. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.2524] [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: 10/24/2022] Open
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82
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Sitte HH, Venkatesan S, Sohail A, Saha K, Jayaraman K, Ecker GF, Freissmuth M, Sandtner W, Stockner T. Transporters in Motion: Combining Computational Approaches and LRET-Measurements. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.1101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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83
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Sitte HH, Freissmuth M. Amphetamines, new psychoactive drugs and the monoamine transporter cycle. Trends Pharmacol Sci 2014; 36:41-50. [PMID: 25542076 PMCID: PMC4502921 DOI: 10.1016/j.tips.2014.11.006] [Citation(s) in RCA: 178] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 11/25/2014] [Accepted: 11/25/2014] [Indexed: 01/05/2023]
Abstract
In monoaminergic neurons, the vesicular transporters and the plasma membrane transporters operate in a relay. Amphetamine and its congeners target this relay to elicit their actions: most amphetamines are substrates, which pervert the relay to elicit efflux of monoamines into the synaptic cleft. However, some amphetamines act as transporter inhibitors. Both compound classes elicit profound psychostimulant effects, which render them liable to recreational abuse. Currently, a surge of new psychoactive substances occurs on a global scale. Chemists bypass drug bans by ingenuous structural variations, resulting in a rich pharmacology. A credible transport model must account for their distinct mode of action and link this to subtle differences in activity and undesired, potentially deleterious effects.
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Affiliation(s)
- Harald H Sitte
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University Vienna, Waehringerstrasse 13A, 1090 Vienna, Austria; Center for Addiction Research and Science (AddRess), Medical University Vienna, Waehringerstrasse 13A, 1090 Vienna, Austria.
| | - Michael Freissmuth
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University Vienna, Waehringerstrasse 13A, 1090 Vienna, Austria
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84
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Anderluh A, Klotzsch E, Ries J, Reismann AWAF, Weber S, Fölser M, Koban F, Freissmuth M, Sitte HH, Schütz GJ. Tracking single serotonin transporter molecules at the endoplasmic reticulum and plasma membrane. Biophys J 2014; 106:L33-5. [PMID: 24806941 DOI: 10.1016/j.bpj.2014.03.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 02/22/2014] [Accepted: 03/14/2014] [Indexed: 01/04/2023] Open
Abstract
Transmembrane proteins are synthesized and folded in the endoplasmic reticulum (ER), an interconnected network of flattened sacs or tubes. Up to now, this organelle has eluded a detailed analysis of the dynamics of its constituents, mainly due to the complex three-dimensional morphology within the cellular cytosol, which precluded high-resolution, single-molecule microscopy approaches. Recent evidences, however, pointed out that there are multiple interaction sites between ER and the plasma membrane, rendering total internal reflection microscopy of plasma membrane proximal ER regions feasible. Here we used single-molecule fluorescence microscopy to study the diffusion of the human serotonin transporter at the ER and the plasma membrane. We exploited the single-molecule trajectories to map out the structure of the ER close to the plasma membrane at subdiffractive resolution. Furthermore, our study provides a comparative picture of the diffusional behavior in both environments. Under unperturbed conditions, the majority of proteins showed similar mobility in the two compartments; at the ER, however, we found an additional 15% fraction of molecules moving with 25-fold faster mobility. Upon degradation of the actin skeleton, the diffusional behavior in the plasma membrane was strongly influenced, whereas it remained unchanged in the ER.
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Affiliation(s)
- Andreas Anderluh
- Institute of Applied Physics, Vienna University of Technology, Vienna, Austria
| | - Enrico Klotzsch
- Institute of Applied Physics, Vienna University of Technology, Vienna, Austria.
| | - Jonas Ries
- European Molecular Biology Laboratory, Heidelberg, Germany
| | | | - Stefan Weber
- Institute of Applied Physics, Vienna University of Technology, Vienna, Austria
| | - Martin Fölser
- Institute of Applied Physics, Vienna University of Technology, Vienna, Austria
| | - Florian Koban
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Vienna, Austria
| | - Michael Freissmuth
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Vienna, Austria
| | - Harald H Sitte
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Vienna, Austria
| | - Gerhard J Schütz
- Institute of Applied Physics, Vienna University of Technology, Vienna, Austria.
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85
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Kusek J, Yang Q, Witek M, Gruber CW, Nanoff C, Freissmuth M. Chaperoning of the A1-adenosine receptor by endogenous adenosine - an extension of the retaliatory metabolite concept. Mol Pharmacol 2014; 87:39-51. [PMID: 25354767 DOI: 10.1124/mol.114.094045] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [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
Cell-permeable orthosteric ligands can assist folding of G protein-coupled receptors in the endoplasmic reticulum (ER); this pharmacochaperoning translates into increased cell surface levels of receptors. Here we used a folding-defective mutant of human A1-adenosine receptor as a sensor to explore whether endogenously produced adenosine can exert a chaperoning effect. This A1-receptor-Y(288)A was retained in the ER of stably transfected human embryonic kidney 293 cells but rapidly reached the plasma membrane in cells incubated with an A1 antagonist. This was phenocopied by raising intracellular adenosine levels with a combination of inhibitors of adenosine kinase, adenosine deaminase, and the equilibrative nucleoside transporter: mature receptors with complex glycosylation accumulated at the cell surface and bound to an A1-selective antagonist with an affinity indistinguishable from the wild-type A1 receptor. The effect of the inhibitor combination was specific, because it did not result in enhanced surface levels of two folding-defective human V2-vasopressin receptor mutants, which were susceptible to pharmacochaperoning by their cognate antagonist. Raising cellular adenosine levels by subjecting cells to hypoxia (5% O2) reproduced chaperoning by the inhibitor combination and enhanced surface expression of A1-receptor-Y(288)A within 1 hour. These findings were recapitulated for the wild-type A1 receptor. Taken together, our observations document that endogenously formed adenosine can chaperone its cognate A1 receptor. This results in a positive feedback loop that has implications for the retaliatory metabolite concept of adenosine action: if chaperoning by intracellular adenosine results in elevated cell surface levels of A1 receptors, these cells will be more susceptible to extracellular adenosine and thus more likely to cope with metabolic distress.
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Affiliation(s)
- Justyna Kusek
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Qiong Yang
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Martin Witek
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Christian W Gruber
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Christian Nanoff
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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86
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Sandtner W, Schmid D, Schicker K, Gerstbrein K, Koenig X, Mayer FP, Boehm S, Freissmuth M, Sitte HH. A quantitative model of amphetamine action on the 5-HT transporter. Br J Pharmacol 2014; 171:1007-18. [PMID: 24251585 PMCID: PMC3925039 DOI: 10.1111/bph.12520] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 10/30/2013] [Accepted: 11/05/2013] [Indexed: 10/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Amphetamines bind to the plasmalemmal transporters for the monoamines dopamine (DAT), noradrenaline (NET) and 5-HT (SERT); influx of amphetamine leads to efflux of substrates. Various models have been proposed to account for this amphetamine-induced reverse transport in mechanistic terms. A most notable example is the molecular stent hypothesis, which posits a special amphetamine-induced conformation that is not likely in alternative access models of transport. The current study was designed to evaluate the explanatory power of these models and the molecular stent hypothesis. EXPERIMENTAL APPROACH Xenopus laevis oocytes and HEK293 cells expressing human (h) SERT were voltage-clamped and exposed to 5-HT, p-chloroamphetamine (pCA) or methylenedioxyamphetamine (MDMA). KEY RESULTS In contrast to the currents induced by 5-HT, pCA-triggered currents through SERT decayed slowly in Xenopus laevis oocytes once the agonist was removed (consistent with the molecular stent hypothesis). However, when SERT was expressed in HEK293 cells, currents induced by 3 or 100 μM pCA decayed 10 or 100 times faster, respectively, after pCA removal. CONCLUSIONS AND IMPLICATIONS This discrepancy in decay rates is inconsistent with the molecular stent hypothesis. In contrast, a multistate version of the alternative access model accounts for all the observations and reproduces the kinetic parameters extracted from the electrophysiological recordings. A crucial feature that explains the action of amphetamines is their lipophilic nature, which allows for rapid diffusion through the membrane.
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Affiliation(s)
- Walter Sandtner
- Center of Physiology and Pharmacology, Medical University Vienna, Vienna, Austria
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87
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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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88
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Douillard P, Hagemann T, Freissmuth M, Thiele M, Schinagl A, Völkel D, Scheiflinger F, Kerschbaumer R. Abstract 2654: Human antibodies specific for oxidized macrophage migration inhibitory factor (oxMIF) synergize with chemotherapeutic agents in animal models of cancer. Cancer Res 2014. [DOI: 10.1158/1538-7445.am2014-2654] [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] [Indexed: 11/16/2022]
Abstract
Abstract
Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine with pleiotropic biologic effects and is pathologically associated with several types of cancer. oxMIF is an immunological and conformational distinct isoform of MIF that can be mimicked in vitro by mild oxidation of recombinant MIF. Fully human monoclonal antibodies that specifically target oxMIF were shown to inhibit downstream signaling pathways associated with tumor proliferation and progression in vitro and in vivo. We assessed the potential of anti-oxMIF antibodies combined with standard chemotherapeutic agents on the proliferation of cancer cell lines in vitro and in vivo in xenograft models. In vitro, anti-oxMIF sensitization of the prostate cancer cell lines PC3 or LnCAP significantly reduced the half maximal effective concentration (EC50) of mitoxantrone by 30% and 40%, respectively. In the ovarian cancer cell lines A2780, EC50 of cisplatin was reduced by 70% after sensitization with anti-oxMIF. In vivo, mice bearing pancreatic cancer xenografts (COLO357, BxPC3 or MiaPaCa2) treated with anti-oxMIF in combination with gemcitabine had a strong survival advantage compared with mice treated with either monotherapy. This effect was accompanied by a decrease of tumor volumes up to 70% and an increase in the expression of caspase 3 in mice bearing COLO357 xenografts. In addition, combining gemcitabine with anti-oxMIF treatment normalized blood vessel density inside the tumors, decreased their permeability by 25%, and decreased tumor VEGF levels by 40%, whereas gemcitabine alone had the opposite effect. In mice bearing the ovarian human cancer cell line A2780 xenografts, combining anti-oxMIF antibodies with cisplatin led to a 45% reduction of tumor weights. Anti-oxMIF specific antibodies decreased proliferation, angiogenesis and inflammation inside tumor xenografts, but were not cytotoxic (no antibody-dependent cell cytotoxicity or complement-dependent cytotoxicity). These experiments demonstrated synergistic effects between anti-oxMIF antibodies and cytotoxic chemotherapy. Combination treatments were superior to the corresponding monotherapies and led to a stronger inhibition of tumor growth and angiogenesis. A phase 1 clinical study of a novel human antibody that selectively targets oxMIF is currently ongoing in patients with solid malignancies (ClinicalTrials.gov identifier: NCT01765790).
Citation Format: Patrice Douillard, Thorsten Hagemann, Michael Freissmuth, Michael Thiele, Alexander Schinagl, Dirk Völkel, Friedrich Scheiflinger, Randolf Kerschbaumer. Human antibodies specific for oxidized macrophage migration inhibitory factor (oxMIF) synergize with chemotherapeutic agents in animal models of cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2654. doi:10.1158/1538-7445.AM2014-2654
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Affiliation(s)
| | - Thorsten Hagemann
- 2Centre for Cancer and Inflammation, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Michael Freissmuth
- 3Institute of Pharmacology, Centre of Physiology and Pharmacology, Medical University, Vienna, Austria
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89
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Schinagl A, Hagemann T, Douillard P, Thiele M, Voelkel D, Freissmuth M, Scheiflinger F, Kerschbaumer RJ. Abstract 4841: Oxidized macrophage migration inhibitory factor (oxMIF) expressed by tumor stroma and tumor cells, contributes to tumor growth. Cancer Res 2014. [DOI: 10.1158/1538-7445.am2014-4841] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Macrophage migration inhibitory factor (MIF) was found to be upregulated in many cancers and to act in para- and autocrine loops within the tumor microenvironment. MIF has pleiotropic effects and plays a role in tumor growth via several mechanisms. (i) MIF acts directly on tumor cells by activating signaling pathways that promote cell proliferation and cell survival. (ii) MIF facilitates invasion of the extracellular matrix and induces angiogenesis and tumor vascularization. (iii) As a proinflammatory cytokine, MIF is one of the mediators of tumor micro-inflammation. However, MIF occurs in two immunologically distinct, redox-dependent isoforms. In its reduced form (redMIF), MIF is abundantly expressed and is present even in healthy subjects. In contrast, oxidized MIF (oxMIF) is found in patients with cancer. Highly selective, fully human monoclonal antibodies that specifically target oxMIF can counter-regulate the biological functions of MIF, indicating that oxMIF is the disease-related isoform of MIF and a relevant drug target. Animal studies and in vitro studies revealed that novel human antibodies that selectively target oxMIF, inhibit proliferation by reducing phosphorylation of ERK1/2 and AKT, promote apoptosis by activating caspase 3, inhibit angiogenesis and metastasis by reducing VEGF expression and blood vessel density within the tumor, and decrease cancer-associated inflammation of the tumor by downregulating the production of proinflammatory cytokines. We used MIF wild type (wt) and MIF knockout (KO) murine pancreatic cancer cells and MIF wt and MIF KO mice with C57Bl/6 background to dissect the contribution of stromal versus tumor derived MIF to tumor progression. Transfer of a pancreatic cancer cell line expressing MIF into wt mice or MIF KO mice resulted in aggressive tumor growth, liver metastasis, and survival of approximately 30 days in both models. Similar results were obtained by transferring a MIF KO pancreatic cancer cell line into MIF wt mice. Only transfer of a MIF KO cell line into MIF KO mice led to improved overall survival of approximately 80 days and completely abrogated metastasis. In a tumor xenograft model, an intravenously applied oxMIF-specific fully human antibody was able to penetrate the cancerous tissue and was detected in the stroma and the tumor. We conclude that both tumor stroma and tumor cells are an efficient source of oxMIF to promote tumor growth and metastasis, and that anti-oxMIF antibodies are able to neutralize oxMIF in the stroma and the tumor. A phase 1 clinical study of a novel human antibody that selectively targets oxMIF is currently ongoing in patients with solid malignancies (ClinicalTrials.gov identifier: NCT01765790).
Citation Format: Alexander Schinagl, Thorsten Hagemann, Patrice Douillard, Michael Thiele, Dirk Voelkel, Michael Freissmuth, Friedrich Scheiflinger, Randolf J. Kerschbaumer. Oxidized macrophage migration inhibitory factor (oxMIF) expressed by tumor stroma and tumor cells, contributes to tumor growth. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4841. doi:10.1158/1538-7445.AM2014-4841
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Affiliation(s)
- Alexander Schinagl
- 1Baxter Biomedical Research Center, Baxter Innovations GmbH, Orth/Donau, Austria
| | - Thorsten Hagemann
- 2Centre for Cancer and Inflammation, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Patrice Douillard
- 1Baxter Biomedical Research Center, Baxter Innovations GmbH, Orth/Donau, Austria
| | - Michael Thiele
- 1Baxter Biomedical Research Center, Baxter Innovations GmbH, Orth/Donau, Austria
| | - Dirk Voelkel
- 1Baxter Biomedical Research Center, Baxter Innovations GmbH, Orth/Donau, Austria
| | - Michael Freissmuth
- 3Institute of Pharmacology, Centre of Physiology and Pharmacology, Medical University Vienna, Vienna, Austria
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90
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Bures C, Bobak-Wieser R, Koppitsch C, Klatte T, Zielinski V, Freissmuth M, Friedrich G, Repasi R, Hermann M. Late-onset palsy of the recurrent laryngeal nerve after thyroid surgery. Br J Surg 2014; 101:1556-9. [DOI: 10.1002/bjs.9648] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Revised: 07/03/2014] [Accepted: 08/12/2014] [Indexed: 12/25/2022]
Abstract
Abstract
Background
A small subset of patients may develop late-onset palsy of the recurrent laryngeal nerve (RLN) after thyroid surgery. However, no conclusive data have been published regarding the incidence of, and possible risk factors for, this complication.
Methods
Preoperative, intraoperative and postoperative data from consecutive patients who underwent thyroid surgery at a single centre between 1999 and 2012 were analysed. Late-onset palsy of the RLN was defined as deterioration of RLN function after normal vocal cord function as investigated by routine preoperative and postoperative laryngoscopy.
Results
The cohort included 16 692 patients with 28 757 nerves at risk. Early postoperative palsy of the RLN was diagnosed in 1183 nerves at risk (4·1 per cent), whereas late-onset RLN palsy was found in 41 (0·1 per cent). Late-onset palsy of the RLN was diagnosed after a median interval of 2·5 (range 0·5–12) weeks and nerve function recovered completely in 28 patients after a median interval of 3 months. This recovery rate was significantly lower than that for early-onset RLN palsy: 1068 (90·3 per cent) of 1183 nerves (P < 0·001). No particular risk factor for late-onset RLN palsy was identified.
Conclusion
Late-onset palsy of the RLN was diagnosed in a small subset of patients after thyroid surgery, and recovery of nerve function occurred less frequently than in patients with early-onset RLN palsy.
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Affiliation(s)
- C Bures
- Second Department of Surgery, Krankenanstalt Rudolfstiftung, Vienna, Austria
- Department of Surgery, Kaiserin-Elisabeth-Spital, Vienna, Austria
| | - R Bobak-Wieser
- Second Department of Surgery, Krankenanstalt Rudolfstiftung, Vienna, Austria
- Department of Surgery, Kaiserin-Elisabeth-Spital, Vienna, Austria
| | - C Koppitsch
- Second Department of Surgery, Krankenanstalt Rudolfstiftung, Vienna, Austria
- Department of Surgery, Kaiserin-Elisabeth-Spital, Vienna, Austria
| | - T Klatte
- Second Department of Surgery, Krankenanstalt Rudolfstiftung, Vienna, Austria
- Department of Urology, Medical University of Vienna, Vienna, Austria
| | - V Zielinski
- Department of Otorhinolaryngology, Krankenanstalt Rudolfstiftung, Vienna, Austria
| | - M Freissmuth
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | - G Friedrich
- Ear, Nose and Throat, University Hospital Graz, Department of Phoniatrics, Medical University of Graz, Graz, Austria
| | - R Repasi
- Department of Otorhinolaryngology, Krankenanstalt Rudolfstiftung, Vienna, Austria
| | - M Hermann
- Second Department of Surgery, Krankenanstalt Rudolfstiftung, Vienna, Austria
- Department of Surgery, Kaiserin-Elisabeth-Spital, Vienna, Austria
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91
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El-Kasaby A, Koban F, Sitte HH, Freissmuth M, Sucic S. A cytosolic relay of heat shock proteins HSP70-1A and HSP90β monitors the folding trajectory of the serotonin transporter. J Biol Chem 2014; 289:28987-9000. [PMID: 25202009 PMCID: PMC4200255 DOI: 10.1074/jbc.m114.595090] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Mutations in the C terminus of the serotonin transporter (SERT) disrupt folding and export from the endoplasmic reticulum. Here we examined the hypothesis that a cytosolic heat shock protein relay was recruited to the C terminus to assist folding of SERT. This conjecture was verified by the following observations. (i) The proximal portion of the SERT C terminus conforms to a canonical binding site for DnaK/heat shock protein of 70 kDa (HSP70). A peptide covering this segment stimulated ATPase activity of purified HSP70-1A. (ii) A GST fusion protein comprising the C terminus of SERT pulled down HSP70-1A. The interaction between HSP70-1A and SERT was visualized in live cells by Förster resonance energy transfer: it was restricted to endoplasmic reticulum-resident transporters and enhanced by an inhibitor that traps HSP70-1A in its closed state. (iv) Co-immunoprecipitation confirmed complex formation of SERT with HSP70-1A and HSP90β. Consistent with an HSP relay, co-chaperones (e.g. HSC70-HSP90-organizing protein) were co-immunoprecipitated with the stalled mutants SERT-R607A/I608A and SERT-P601A/G602A. (v) Depletion of HSP90β by siRNA or its inhibition increased the cell surface expression of wild type SERT and SERT-F604Q. In contrast, SERT-R607A/I608A and SERT-P601A/G602A were only rendered susceptible to inhibition of HSP70 and HSP90 by concomitant pharmacochaperoning with noribogaine. (vi) In JAR cells, inhibition of HSP90 also increased the levels of SERT, indicating that endogenously expressed transporter was also susceptible to control by HSP90β. These findings support the concept that the folding trajectory of SERT is sampled by a cytoplasmic chaperone relay.
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Affiliation(s)
- Ali El-Kasaby
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and the Department of Pharmacology, Faculty of Veterinary Medicine, Mansoura University, 35516 Mansoura, Egypt
| | - Florian Koban
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and
| | - Harald H Sitte
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and
| | - Michael Freissmuth
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and
| | - Sonja Sucic
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and
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92
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Michl J, Scharinger C, Zauner M, Kasper S, Freissmuth M, Sitte HH, Ecker GF, Pezawas L. A multivariate approach linking reported side effects of clinical antidepressant and antipsychotic trials to in vitro binding affinities. Eur Neuropsychopharmacol 2014; 24:1463-74. [PMID: 25044049 PMCID: PMC4502613 DOI: 10.1016/j.euroneuro.2014.06.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 06/23/2014] [Accepted: 06/26/2014] [Indexed: 01/01/2023]
Abstract
The vast majority of approved antidepressants and antipsychotics exhibit a complex pharmacology. The mechanistic understanding of how these psychotropic medications are related to adverse drug reactions (ADRs) is crucial for the development of novel drug candidates and patient adherence. This study aims to associate in vitro assessed binding affinity profiles (39 compounds, 24 molecular drug targets) and ADRs (n=22) reported in clinical trials of antidepressants and antipsychotics (n>59.000 patients) by the use of robust multivariate statistics. Orthogonal projection to latent structures (O-PLS) regression models with reasonable predictability were found for several frequent ADRs such as nausea, diarrhea, hypotension, dizziness, headache, insomnia, sedation, sleepiness, increased sweating, and weight gain. Results of the present study support many well-known pharmacological principles such as the association of hypotension and dizziness with α1-receptor or sedation with H1-receptor antagonism. Moreover, the analyses revealed novel or hardly investigated mechanisms for common ADRs including the potential involvement of 5-HT6-antagonism in weight gain, muscarinic receptor antagonism in dizziness, or 5-HT7-antagonism in sedation. To summarize, the presented study underlines the feasibility and value of a multivariate data mining approach in psychopharmacological development of antidepressants and antipsychotics.
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Affiliation(s)
- Johanna Michl
- Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - Christian Scharinger
- Department of Psychiatry and Psychotherapy, Medical University Vienna, Vienna, Austria
| | - Miriam Zauner
- Department of Psychiatry and Psychotherapy, Medical University Vienna, Vienna, Austria
| | - Siegfried Kasper
- Department of Psychiatry and Psychotherapy, Medical University Vienna, Vienna, Austria
| | | | - Harald H Sitte
- Department of Pharmacology, Medical University Vienna, Vienna, Austria
| | - Gerhard F Ecker
- Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria.
| | - Lukas Pezawas
- Department of Psychiatry and Psychotherapy, Medical University Vienna, Vienna, Austria
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93
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Burtscher V, Schicker K, Novikova E, Pöhn B, Stockner T, Kugler C, Singh A, Zeitz C, Lancelot ME, Audo I, Leroy BP, Freissmuth M, Herzig S, Matthes J, Koschak A. Spectrum of Cav1.4 dysfunction in congenital stationary night blindness type 2. Biochim Biophys Acta 2014; 1838:2053-65. [PMID: 24796500 PMCID: PMC4065569 DOI: 10.1016/j.bbamem.2014.04.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 04/11/2014] [Accepted: 04/23/2014] [Indexed: 11/26/2022]
Abstract
Defective retinal synaptic transmission in patients affected with congenital stationary night blindness type 2 (CSNB2) can result from different dysfunction phenotypes in Cav1.4 L-type calcium channels. Here we investigated two prototypical Cav1.4 variants from either end of the functional spectrum. Using whole-cell and single-channel patch-clamp techniques, we provide analysis of the biophysical characteristics of the point mutation L860P and the C-terminal truncating mutation R1827X. L860P showed a typical loss-of-function phenotype attributed to a reduced number of functional channels expressed at the plasma membrane as implied by gating current and non-stationary noise analyses. This phenotype can be rationalized, because the inserted proline is predicted to break an amphipatic helix close to the transmembrane segment IIIS1 and thus to reduce channel stability and promote misfolding. In fact, L860P was subject to an increased turnover. In contrast, R1827X displayed an apparent gain-of-function phenotype, i.e., due to a hyperpolarizing shift of the IV-curve and increased single-channel activity. However, truncation also resulted in the loss of functional C-terminal modulation and thus unmasked calcium-dependent inactivation. Thus R1827X failed to support continuous calcium influx. Current inactivation curtails the dynamic range of photoreceptors (e.g., when adapting to variation in illumination). Taken together, the analysis of two representative mutations that occur in CSNB2 patients revealed fundamental differences in the underlying defect. These may explain subtle variations in the clinical manifestation and must be taken into account, if channel function is to be restored by pharmacochaperones or related approaches.
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Affiliation(s)
- Verena Burtscher
- Medical University Vienna, Center for Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Schwarzspanierstrasse 17, 1090 Vienna, Austria
| | - Klaus Schicker
- Medical University Vienna, Center for Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Schwarzspanierstrasse 17, 1090 Vienna, Austria
| | - Elena Novikova
- University of Cologne, Department of Pharmacology and Center of Molecular Medicine, 50931 Cologne, Germany
| | - Birgit Pöhn
- Medical University Vienna, Center for Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Schwarzspanierstrasse 17, 1090 Vienna, Austria
| | - Thomas Stockner
- Medical University Vienna, Center for Physiology and Pharmacology, Department of Pharmacology, Währingerstrasse 13A, 1090 Wien, Austria
| | - Christof Kugler
- Medical University Vienna, Center for Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Schwarzspanierstrasse 17, 1090 Vienna, Austria
| | - Anamika Singh
- University of Innsbruck, Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, Innrain 80-82/III, 6020 Innsbruck, Austria
| | - Christina Zeitz
- INSERM, UMR_S968, Paris F-75012, France; CNRS, UMR_7210, Paris F-75012, France; UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris F-75012, France
| | - Marie-Elise Lancelot
- INSERM, UMR_S968, Paris F-75012, France; CNRS, UMR_7210, Paris F-75012, France; UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris F-75012, France
| | - Isabelle Audo
- INSERM, UMR_S968, Paris F-75012, France; CNRS, UMR_7210, Paris F-75012, France; UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris F-75012, France; Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 503, Paris F-75012, France; UCL-Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Bart Peter Leroy
- Dept of Ophthalmology & Center for Medical Genetics, Ghent University Hospital & Ghent University, 9000 Ghent, Belgium
| | - Michael Freissmuth
- Medical University Vienna, Center for Physiology and Pharmacology, Department of Pharmacology, Währingerstrasse 13A, 1090 Wien, Austria
| | - Stefan Herzig
- University of Cologne, Department of Pharmacology and Center of Molecular Medicine, 50931 Cologne, Germany
| | - Jan Matthes
- University of Cologne, Department of Pharmacology and Center of Molecular Medicine, 50931 Cologne, Germany
| | - Alexandra Koschak
- Medical University Vienna, Center for Physiology and Pharmacology, Department of Neurophysiology and -pharmacology, Schwarzspanierstrasse 17, 1090 Vienna, Austria.
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94
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Thiele M, Hagemann T, Freissmuth M, Douillard P, Völkel D, Scheiflinger F, Kerschbaumer R. 811: Fully human antibodies specific for oxidized macrophage migration inhibitory factor (oxMIF) exhibit anti-cancer activity in animal models. Eur J Cancer 2014. [DOI: 10.1016/s0959-8049(14)50716-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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95
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Scharinger C, Rabl U, Kasess CH, Meyer BM, Hofmaier T, Diers K, Bartova L, Pail G, Huf W, Uzelac Z, Hartinger B, Kalcher K, Perkmann T, Haslacher H, Meyer-Lindenberg A, Kasper S, Freissmuth M, Windischberger C, Willeit M, Lanzenberger R, Esterbauer H, Brocke B, Moser E, Sitte HH, Pezawas L. Platelet serotonin transporter function predicts default-mode network activity. PLoS One 2014; 9:e92543. [PMID: 24667541 PMCID: PMC3965432 DOI: 10.1371/journal.pone.0092543] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 02/25/2014] [Indexed: 12/16/2022] Open
Abstract
Background The serotonin transporter (5-HTT) is abundantly expressed in humans by the serotonin transporter gene SLC6A4 and removes serotonin (5-HT) from extracellular space. A blood-brain relationship between platelet and synaptosomal 5-HT reuptake has been suggested, but it is unknown today, if platelet 5-HT uptake can predict neural activation of human brain networks that are known to be under serotonergic influence. Methods A functional magnetic resonance study was performed in 48 healthy subjects and maximal 5-HT uptake velocity (Vmax) was assessed in blood platelets. We used a mixed-effects multilevel analysis technique (MEMA) to test for linear relationships between whole-brain, blood-oxygen-level dependent (BOLD) activity and platelet Vmax. Results The present study demonstrates that increases in platelet Vmax significantly predict default-mode network (DMN) suppression in healthy subjects independent of genetic variation within SLC6A4. Furthermore, functional connectivity analyses indicate that platelet Vmax is related to global DMN activation and not intrinsic DMN connectivity. Conclusion This study provides evidence that platelet Vmax predicts global DMN activation changes in healthy subjects. Given previous reports on platelet-synaptosomal Vmax coupling, results further suggest an important role of neuronal 5-HT reuptake in DMN regulation.
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Affiliation(s)
- Christian Scharinger
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Ulrich Rabl
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Christian H. Kasess
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Bernhard M. Meyer
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Tina Hofmaier
- Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria
- Center for Biomolecular Medicine and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Kersten Diers
- Department of Psychology, Dresden University of Technology, Dresden, Germany
| | - Lucie Bartova
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Gerald Pail
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Wolfgang Huf
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
- Department of Statistics and Probability Theory, Vienna University of Technology, Vienna, Austria
| | - Zeljko Uzelac
- Center for Biomolecular Medicine and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Beate Hartinger
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Klaudius Kalcher
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
- Department of Statistics and Probability Theory, Vienna University of Technology, Vienna, Austria
| | - Thomas Perkmann
- Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria
| | - Helmuth Haslacher
- Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria
| | | | - Siegfried Kasper
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Michael Freissmuth
- Center for Biomolecular Medicine and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Christian Windischberger
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Matthäus Willeit
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Rupert Lanzenberger
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Harald Esterbauer
- Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria
| | - Burkhard Brocke
- Department of Psychology, Dresden University of Technology, Dresden, Germany
| | - Ewald Moser
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Harald H. Sitte
- Center for Biomolecular Medicine and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Lukas Pezawas
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
- * E-mail:
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96
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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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97
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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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98
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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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99
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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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100
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Kollmann K, Heller G, Schneckenleithner C, Warsch W, Scheicher R, Ott R, Schäfer M, Fajmann S, Schlederer M, Schiefer AI, Reichart U, Mayerhofer M, Hoeller C, Zöchbauer-Müller S, Kerjaschki D, Bock C, Kenner L, Hoefler G, Freissmuth M, Green A, Moriggl R, Busslinger M, Malumbres M, Sexl V. A kinase-independent function of CDK6 links the cell cycle to tumor angiogenesis. Cancer Cell 2013; 24:167-81. [PMID: 23948297 PMCID: PMC3743049 DOI: 10.1016/j.ccr.2013.07.012] [Citation(s) in RCA: 197] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 05/17/2013] [Accepted: 07/22/2013] [Indexed: 12/20/2022]
Abstract
In contrast to its close homolog CDK4, the cell cycle kinase CDK6 is expressed at high levels in lymphoid malignancies. In a model for p185BCR-ABL+ B-acute lymphoid leukemia, we show that CDK6 is part of a transcription complex that induces the expression of the tumor suppressor p16INK4a and the pro-angiogenic factor VEGF-A. This function is independent of CDK6's kinase activity. High CDK6 expression thus suppresses proliferation by upregulating p16INK4a, providing an internal safeguard. However, in the absence of p16INK4a, CDK6 can exert its full tumor-promoting function by enhancing proliferation and stimulating angiogenesis. The finding that CDK6 connects cell-cycle progression to angiogenesis confirms CDK6's central role in hematopoietic malignancies and could underlie the selection pressure to upregulate CDK6 and silence p16INK4a.
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Affiliation(s)
- Karoline Kollmann
- Institute of Pharmacology and Toxicology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Gerwin Heller
- Clinical Division of Oncology, Department of Medicine I, Comprehensive Cancer Center, Medical University of Vienna, 1090 Vienna, Austria
| | | | - Wolfgang Warsch
- Institute of Pharmacology and Toxicology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Ruth Scheicher
- Institute of Pharmacology and Toxicology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Rene G. Ott
- Institute of Pharmacology, Center of Biomolecular Medicine and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Markus Schäfer
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Sabine Fajmann
- Institute of Pharmacology and Toxicology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Michaela Schlederer
- Department of Clinical Pathology, Medical University of Vienna, 1090 Vienna, Austria
| | - Ana-Iris Schiefer
- Department of Clinical Pathology, Medical University of Vienna, 1090 Vienna, Austria
| | - Ursula Reichart
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Matthias Mayerhofer
- Department of Laboratory Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - Christoph Hoeller
- Department of Dermatology, Medical University of Vienna, 1090 Vienna, Austria
| | - Sabine Zöchbauer-Müller
- Clinical Division of Oncology, Department of Medicine I, Comprehensive Cancer Center, Medical University of Vienna, 1090 Vienna, Austria
| | - Dontscho Kerjaschki
- Department of Clinical Pathology, Medical University of Vienna, 1090 Vienna, Austria
| | - Christoph Bock
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Lukas Kenner
- Ludwig Boltzmann Institute for Cancer Research, 1090 Vienna, Austria
| | - Gerald Hoefler
- Department of Pathology, Medical University of Graz, 8036 Graz, Austria
| | - Michael Freissmuth
- Institute of Pharmacology, Center of Biomolecular Medicine and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Anthony R. Green
- Cambridge Institute for Medical Research and Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge CB2 0XY, UK
- Department of Hematology, University of Cambridge, Cambridge CB2 0XY, UK
- Department of Hematology, Addenbrooke’s Hospital, Cambridge CB2 0XY, UK
| | - Richard Moriggl
- Ludwig Boltzmann Institute for Cancer Research, 1090 Vienna, Austria
| | - Meinrad Busslinger
- Institute of Pharmacology, Center of Biomolecular Medicine and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Marcos Malumbres
- Cell Division and Cancer Group, Molecular Oncology Programme, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain
| | - Veronika Sexl
- Institute of Pharmacology and Toxicology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
- Corresponding author
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