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Mayer FP, Schmid D, Owens WA, Gould GG, Apuschkin M, Kudlacek O, Salzer I, Boehm S, Chiba P, Williams PH, Wu HH, Gether U, Koek W, Daws LC, Sitte HH. An unsuspected role for organic cation transporter 3 in the actions of amphetamine. Neuropsychopharmacology 2018; 43:2408-2417. [PMID: 29773909 PMCID: PMC6180071 DOI: 10.1038/s41386-018-0053-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 03/19/2018] [Accepted: 03/21/2018] [Indexed: 01/11/2023]
Abstract
Amphetamine abuse is a major public health concern for which there is currently no effective treatment. To develop effective treatments, the mechanisms by which amphetamine produces its abuse-related effects need to be fully understood. It is well known that amphetamine exerts its actions by targeting high-affinity transporters for monoamines, in particular the cocaine-sensitive dopamine transporter. Organic cation transporter 3 (OCT3) has recently been found to play an important role in regulating monoamine signaling. However, whether OCT3 contributes to the actions of amphetamine is unclear. We found that OCT3 is expressed in dopamine neurons. Then, applying a combination of in vivo, ex vivo, and in vitro approaches, we revealed that a substantial component of amphetamine's actions is OCT3-dependent and cocaine insensitive. Our findings support OCT3 as a new player in the actions of amphetamine and encourage investigation of this transporter as a potential new target for the treatment of psychostimulant abuse.
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Affiliation(s)
- Felix P. Mayer
- 0000 0000 9259 8492grid.22937.3dCenter for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Diethart Schmid
- 0000 0000 9259 8492grid.22937.3dCenter for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - W. Anthony Owens
- 0000 0001 0629 5880grid.267309.9Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229 USA
| | - Georgianna G. Gould
- 0000 0001 0629 5880grid.267309.9Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229 USA
| | - Mia Apuschkin
- 0000 0001 0674 042Xgrid.5254.6Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Panum Institute 18.6, 2200 Copenhagen N, Denmark
| | - Oliver Kudlacek
- 0000 0000 9259 8492grid.22937.3dCenter for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Isabella Salzer
- 0000 0000 9259 8492grid.22937.3dCenter for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Stefan Boehm
- 0000 0000 9259 8492grid.22937.3dCenter for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Peter Chiba
- 0000 0000 9259 8492grid.22937.3dInstitute of Medical Chemistry, Medical University of Vienna, 1090 Vienna, Austria
| | - Piper H. Williams
- 0000 0001 2156 6853grid.42505.36Department of Pediatrics, The Saban Research Institute, Children’s Hospital Los Angeles, Keck School of Medicine of USC, 4661 Sunset Blvd. Rm 307, Los Angeles, CA 90027 USA
| | - Hsiao-Huei Wu
- 0000 0001 2156 6853grid.42505.36Department of Pediatrics, The Saban Research Institute, Children’s Hospital Los Angeles, Keck School of Medicine of USC, 4661 Sunset Blvd. Rm 307, Los Angeles, CA 90027 USA
| | - Ulrik Gether
- 0000 0001 0674 042Xgrid.5254.6Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Panum Institute 18.6, 2200 Copenhagen N, Denmark
| | - Wouter Koek
- 0000 0001 0629 5880grid.267309.9Department of Psychiatry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229 USA ,0000 0001 0629 5880grid.267309.9Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229 USA
| | - Lynette C. Daws
- 0000 0001 0629 5880grid.267309.9Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229 USA ,0000 0001 0629 5880grid.267309.9Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229 USA
| | - Harald H. Sitte
- 0000 0000 9259 8492grid.22937.3dCenter for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria ,0000 0000 9259 8492grid.22937.3dCenter for Addiction Research and Science, Medical University Vienna, Waehringerstrasse 13 A, 1090 Vienna, Austria
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Lemmer K, Ahnert-Hilger G, Höpfner M, Hoegerle S, Faiss S, Grabowski P, Jockers-Scherübl M, Riecken EO, Zeitz M, Scherübl H. Expression of dopamine receptors and transporter in neuroendocrine gastrointestinal tumor cells. Life Sci 2002; 71:667-78. [PMID: 12072155 DOI: 10.1016/s0024-3205(02)01703-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
C-11- or F-18-DOPA positron emission tomography (DOPA PET) is a new sensitive imaging technique for small neuroendocrine gastrointestinal tumors which evaluates the decarboxylase activity. To further characterize the dopaminergic system in neuroendocrine gastrointestinal tumor cells, we investigated the expression of both dopamine receptors and the transmembrane dopamine transporter (DAT) in the human neuroendocrine pancreatic cell line BON and in the neuroendocrine gut cell line STC-1. Both BON and STC-1 cells expressed mRNA of the dopamine receptors D2-D5 and DAT. mRNA of the dopamine receptor D1 was detected in BON cells only. Both in BON and STC-1 cells, expression of D2 and D5 receptors and DAT was also demonstrated immunocytochemically. For functional receptor characterization intracellular cAMP levels ([cAMP]i) were determined. Whereas in STC-1 cells dopamine and the D1-like (D1/D5) receptor agonist SKF 38393 increased [cAMP]i, [cAMP]i was decreased by dopamine or the D2-like (D2-D4) receptor agonist quinpirole in BON cells. Functional DAT activity was, however, not detected in either cell line. The presence of both dopamine receptors and of the DAT suggests an autocrine and/or paracrine function of dopamine in neuroendocrine gastrointestinal tumor cells. Yet neither the transmembrane dopamine transporter nor dopamine receptors are likely to contribute to positive DOPA PET imaging of neuroendocrine gastrointestinal tumors. However, these molecules may be of diagnostic importance when applying other dopaminergic system tracers.
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MESH Headings
- 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine/pharmacology
- Animals
- Base Sequence
- Biological Transport
- Colforsin/pharmacology
- Cyclic AMP/metabolism
- DNA Primers
- Dopamine/metabolism
- Dopamine/pharmacology
- Dopamine Plasma Membrane Transport Proteins
- Gastrointestinal Neoplasms
- Gene Expression Regulation, Neoplastic
- Humans
- Membrane Glycoproteins
- Membrane Transport Proteins/genetics
- Mice
- Nerve Tissue Proteins
- Neuroendocrine Tumors/genetics
- Pancreatic Neoplasms
- Quinpirole/pharmacology
- RNA, Messenger/genetics
- Receptors, Dopamine/genetics
- Receptors, Dopamine D1/genetics
- Receptors, Dopamine D2/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Transcription, Genetic
- Tumor Cells, Cultured
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Affiliation(s)
- K Lemmer
- Med. Klinik I, Universitätsklinikum Benjamin Franklin, FU, Berlin, Germany
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Chen N, Vaughan RA, Reith ME. The role of conserved tryptophan and acidic residues in the human dopamine transporter as characterized by site-directed mutagenesis. J Neurochem 2001; 77:1116-27. [PMID: 11359877 DOI: 10.1046/j.1471-4159.2001.00312.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The human dopamine (DA) transporter (hDAT) contains multiple tryptophans and acidic residues that are completely or highly conserved among Na(+)/Cl(-)-dependent transporters. We have explored the roles of these residues using non-conservative substitution. Four of 17 mutants (E117Q, W132L, W177L and W184L) lacked plasma membrane immunostaining and were not functional. Both DA uptake and cocaine analog (i.e. 2beta-carbomethoxy-3beta-(4-fluorophenyl)tropane, CFT) binding were abolished in W63L and severely damaged in W311L. Four of five aspartate mutations (D68N, D313N, D345N and D436N) shifted the relative selectivity of the hDAT for cocaine analogs and DA by 10-24-fold. In particular, mutation of D345 in the third intracellular loop still allowed considerable [(3)H]DA uptake, but caused undetectable [(3)H]CFT binding. Upon anti-C-terminal-hDAT immunoblotting, D345N appeared as broad bands of 66-97 kDa, but this band could not be photoaffinity labeled with cocaine analog [(125)I]-3beta-(p-chlorophenyl)tropane-2beta-carboxylic acid ([(125)I]RTI-82). Unexpectedly, in this mutant, cocaine-like drugs remained potent inhibitors of [(3)H]DA uptake. CFT solely raised the K(m) of [(3)H]DA uptake in wild-type hDAT, but increased K(m) and decreased V(max) in D345N, suggesting different mechanisms of inhibition. The data taken together indicate that mutation of conserved tryptophans or acidic residues in the hDAT greatly impacts ligand recognition and substrate transport. Additionally, binding of cocaine to the transporter may not be the only way by which cocaine analogs inhibit DA uptake.
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Affiliation(s)
- N Chen
- Department of Biomedical and Therapeutic Sciences, University of Illinois College of Medicine, Peoria, Illinois, USA
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Eisenhofer G. The role of neuronal and extraneuronal plasma membrane transporters in the inactivation of peripheral catecholamines. Pharmacol Ther 2001; 91:35-62. [PMID: 11707293 DOI: 10.1016/s0163-7258(01)00144-9] [Citation(s) in RCA: 231] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Catecholamines are translocated across plasma membranes by transporters that belong to two large families with mainly neuronal or extraneuronal locations. In mammals, neuronal uptake of catecholamines involves the dopamine transporter (DAT) at dopaminergic neurons and the norepinephrine transporter (NET) at noradrenergic neurons. Extraneuronal uptake of catecholamines is mediated by organic cation transporters (OCTs), including the classic corticosterone-sensitive extraneuronal monoamine transporter. Catecholamine transporters function as part of uptake and metabolizing systems primarily responsible for inactivation of transmitter released by neurons. Additionally, the neuronal catecholamine transporters, recycle catecholamines for rerelease, thereby reducing requirements for transmitter synthesis. In a broader sense, catecholamine transporters function as part of integrated systems where catecholamine synthesis, release, uptake, and metabolism are regulated in a coordinated fashion in response to the demands placed on the system. Location is also important to function. Neuronal transporters are essential for rapid termination of the signal in neuronal-effector organ transmission, whereas non-neuronal transporters are more important for limiting the spread of the signal and for clearance of catecholamines from the bloodstream. Besides their presynaptic locations, NET and DAT are also present at several extraneuronal locations, including syncytiotrophoblasts of the placenta and endothelial cells of the lung (NET), stomach and pancreas (DAT). The extraneuronal monoamine transporter shows a broad tissue distribution, whereas the other two non-neuronal catecholamine transporters (OCT1 and OCT2) are mainly localized to the liver, kidney, and intestine. Altered function of peripheral catecholamine transporters may be involved in disturbances of the autonomic nervous system, such as occurs in congestive heart failure and hypernoradrenergic hypertension. Peripheral catecholamine transporters provide important targets for clinical imaging of sympathetic nerves and diagnostic localization and treatment of neuroendocrine tumors, such as neuroblastomas and pheochromocytomas.
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Affiliation(s)
- G Eisenhofer
- Clinical Neurocardiology Section, National Institute of Neurological Disorders and Stroke, Building 10, Room 6N 252, National Institutes of Health, 10 Center Drive, MSC 1620, Bethesda, MD 20892-1620, USA.
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Miller GM, Yatin SM, De La Garza R, Goulet M, Madras BK. Cloning of dopamine, norepinephrine and serotonin transporters from monkey brain: relevance to cocaine sensitivity. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2001; 87:124-43. [PMID: 11223167 DOI: 10.1016/s0169-328x(00)00288-6] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We used RT-PCR to clone monoamine transporters from Macaca mulatta, Macaca fasicularis and Saimiri sciureus (dopamine transporter; DAT) and Macaca mulatta (norepinephrine transporter; NET and serotonin transporter; SERT). Monkey DAT, NET and SERT proteins were >98% homologous to human and, when expressed in HEK-293 cells, displayed drug affinities and uptake kinetics that were highly correlated with monkey brain or human monoamine transporters. In contrast to reports of other species, we discovered double (leucine for phenylalanine 143 and arginine for glutamine 509; Variant I) and single (proline for leucine 355; Variant II) amino acid variants of DAT. Variant I displayed dopamine transport kinetics and binding affinities for various DAT blockers (including cocaine) versus [3H] CFT (WIN 35, 428) that were identical to wild-type DAT (n=7 drugs; r(2)=0.991). However, we detected a six-fold difference in the affinity of cocaine versus [3H] cocaine between Variant I (IC(50): 488+/-102 nM, SEM, n=3) and wild-type DAT (IC(50): 79+/-8.2 nM, n=3, P<0.05). Variant II was localized intracellularly in HEK-293 cells, as detected by confocal microscopy, and had very low levels of binding and dopamine transport. Also discovered was a novel exon 5 splice variant of NET that displayed very low levels of transport and did not bind cocaine. With NetPhos analysis, we detected a number of highly conserved putative phosphorylation sites on extracellular as well as intracellular loops of the DAT, NET, and SERT, which may be functional for internalized transporters. The homology and functional similarity of human and monkey monoamine transporters further support the value of primates in investigating the role of monoamine transporters in substance abuse mechanisms, neuropsychiatric disorders and development of diagnostic and therapeutic agents.
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Affiliation(s)
- G M Miller
- Harvard Medical School, Division of Neurochemistry, New England Regional Primate Research Center, One Pine Hill Drive, 01772, Southborough, MA, USA
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Abstract
The dopamine transporter mediates uptake of dopamine into neurons and is a major target for various pharmacologically active drugs and environmental toxins. Since its cloning, much information has been obtained regarding its structure and function. Binding domains for dopamine and various blocking drugs including cocaine are likely formed by interactions with multiple amino acid residues, some of which are separate in the primary structure but lie close together in the still unknown tertiary structure. Chimera and site-directed mutagenesis studies suggest the involvement of both overlapping and separate domains in the interaction with substrates and blockers, whereas recent findings with sulfhydryl reagents selectively targeting cysteine residues support a role for conformational changes in the binding of blockers such as cocaine. The dopamine transporter can also operate in reverse, i.e. in an efflux mode, and recent mutagenesis experiments show different structural requirements for inward and outward transport. Strong evidence for dopamine transporter domains selectively influencing binding of dopamine or cocaine analogs has not yet emerged, although the development of a cocaine antagonist at the level of the transporter remains a possibility.
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Affiliation(s)
- N Chen
- Department of Biomedical and Therapeutic Sciences, College of Medicine, University of Illinois, Box 1649, Peoria, IL 61656, USA
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Bleasby K, Chauhan S, Brown CD. Characterization of MPP+ secretion across human intestinal Caco-2 cell monolayers: role of P-glycoprotein and a novel Na(+)-dependent organic cation transport mechanism. Br J Pharmacol 2000; 129:619-25. [PMID: 10711363 PMCID: PMC1571862 DOI: 10.1038/sj.bjp.0703078] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/1999] [Revised: 10/27/1999] [Accepted: 11/08/1999] [Indexed: 01/22/2023] Open
Abstract
1. In the kidney, a number of transport proteins involved in the secretion of permanently charged organic cations have recently been cloned. To evaluate the possible similarities between intestine and kidney in the handling of organic cations we investigated the transport of 1-methyl-4-phenylpyridinium (MPP+) across monolayers of intestinal Caco-2 cells. MPP+ is a prototypic substrate of the cloned organic cation transporters hOCT1 and hOCT2. 2. In Caco-2 cell monolayers, the basolateral to apical flux of MPP+ was significantly greater than the apical to basolateral flux, consistent with net secretion of MPP+. 3. Net secretion of MPP+ was abolished by addition of either 10 microM cyclosporin A or 100 microM verapamil to the apical membrane. In contrast, secretion of MPP+ was unaffected by addition of either TEA (2 mM) or decynium-22 (2 microM) to either apical or basolateral membranes. These results suggest that MPP+ secretion is mediated primarily by P-glycoprotein located at the apical membrane. We found no evidence of a role for hOCT1 or hOCT2 in the secretion of MPP+. 4. In addition to net secretion of MPP+, we found evidence of a Na(+)-dependent MPP+ uptake mechanism at the apical membrane of Caco-2 cells. 5. Na(+)-dependent MPP+ uptake was sensitive to inhibition by the organic cations; decynium-22 (2 microM), TEA (2 mM) and cimetidine (5 mM) but not by carnitine, guanidine or proline. 6. These results suggest that net secretion of MPP+ across the apical membrane of Caco-2 cells is a function of the relative contributions of MPP+ secretion mediated by P-glycoprotein and MPP+ absorption mediated by a novel Na(+)-dependent transport mechanism.
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Affiliation(s)
- K Bleasby
- Department of Physiological Sciences, Medical School, University of Newcastle-upon-Tyne
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