Biogenic amine transporters: Regulation in flux

Current Opinion in Neurobiology

Volumn 10, Issue 3, 2000, Pages 328-336

  Blakely, Randy D ^a   Bauman, Andrea L ^a  

^a VANDERBILT UNIVERSITY SCHOOL OF MEDICINE   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

AMPHETAMINE; BIOGENIC AMINE; COCAINE; DOPAMINE; DOPAMINE TRANSPORTER; NEUROTRANSMITTER; NORADRENALIN; PROTEIN KINASE C; SEROTONIN; SEROTONIN TRANSPORTER;

AMINE TRANSPORT; COGNITIVE DEFECT; DOPAMINE UPTAKE; ENDOCYTOSIS; ENZYME ACTIVATION; HUMAN; NONHUMAN; PRIORITY JOURNAL; PROTEIN PHOSPHORYLATION; REVIEW; SECOND MESSENGER; SEROTONIN UPTAKE;

BIOGENIC MONOAMINES; BIOLOGICAL TRANSPORT; HUMANS; NEURONS; SYNAPTIC TRANSMISSION;

EID: 0034084644     PISSN: 09594388     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0959-4388(00)00088-X     Document Type: Review

References (56)

1. Povlock S.L., Amara S.G. The structure and function of norepinephrine, dopamine, and serotonin transporters. Reith M.E.A. Neurotransmitter Transporters: Structure, Function, and Regulation. 1997;1-28 Humana Press, Totowa NJ.
2. Pacholczyk T., Blakely R.D., Amara S.G. Expression cloning of a cocaine- and antidepressant-sensitive human noradrenaline transporter. Nature. 350:1991;350-354.
3. Guastella J., Nelson N., Nelson H., Czyzyk L., Keynan S., Miedel M.C., Davidson N., Lester H.A., Kanner B.I. Cloning and expression of a rat brain GABA transporter. Science. 249:1990;1303-1306.
4. Giros B., Jaber M., Jones S.R., Wightman R.M., Caron M.G. Hyperlocomotion and indifference to cocaine and amphetamine in mice lacking the dopamine transporter. Nature. 379:1996;606-612.
5. Jones S.R., Gainetdinov R.R., Jaber M., Giros B., Wightman R.M., Caron M.G. Profound neuronal plasticity in response to inactivation of the dopamine transporter. Proc Natl Acad Sci USA. 95:1998;4029-4034. DAT-deficient mice are found to exhibit significant alterations in DA levels, DA synthesis and DA turnover, revealing that appropriate levels of DAT expression dicates other presynaptic determinants of DA signaling.
6. Bengel D., Murphy D.L., Andrews A.M., Wichems C.H., Feltner D., Heils A., Mossner R., Westphal H., Lesch K.P. Altered brain serotonin homeostasis and locomotor insensitivity to 3,4-methylenedioxymetamphetamine ('ecstasy') in serotonin transporter-deficient mice. Mol Pharmacol. 53:1998;649-655. This is the first description of the phenotypes associated with genetically established SERT-deficiency. As with DAT knockouts, SERT disruption influences presynaptic neurotransmitter levels and biosynthesis of 5-HT. SERT-deficient animals fail to display MDMA-induced locomotor activation, supporting the proposal that SERTs are a target for the psychostimulant.
7. Blakely R.D., Ramamoorthy S., Schroeter S., Qian Y., Apparsundaram S., Galli A., DeFelice L.J. Regulated phosphorylation and trafficking of antidepressant-sensitive serotonin transporter proteins. Biol Psych. 44:1998;169-178.
8. Qian Y., Galli A., Ramamoorthy S., Risso S., DeFelice L.J., Blakely R.D. Protein kinase C activation regulates human serotonin transporters in HEK-293 cells via altered cell surface expression. J Neurosci. 17:1997;45-47.
9. Corey J.L., Davidson N., Lester H.A., Brecha N., Quick M.W. Protein kinase C modulates the activity of a cloned γ-aminobutyric acid transporter expressed in Xenopus oocytes via regulated subcellular redistribution of the transporter. J Biol Chem. 269:1994;14759-14767.
10. Quick M.W., Corey J.L., Davidson N., Lester H.A. Second messengers, trafficking-related proteins, and amino acid residues that contribute to the functional regulation of the rat brain GABA transporter GAT1. J Neurosci. 17:1997;2967-2979.
11. Apparsundaram S., Schroeter S., Blakely R.D. Acute regulation of norepinephrine transport. II. PKC-modulated surface expression of human norepinephrine transporter proteins. J Pharmacol Exp Ther. 287:1998;744-751.
12. Pristupa Z.B., McConkey F., Liu F., Man H.Y., Lee F.J., Wang Y.T., Niznik H.B. Protein kinase-mediated bidirectional trafficking and functional regulation of the human dopamine transporter. Synapse. 30:1998;79-87. The authors use confocal microscopy to show that a PKC-mediated decrease in DA uptake in human hDAT-transfected COS cells is a result of transporter internalization. In addition, the increase in transport activity seen with PKC or PKA inhibition is shown to result from the recuritment of intracellular transporters to the surface. These findings reveal bidirectional alterations in the transporter trafficking that supports DAT regulation.
13. Melikian H., Buckley K. Membrane trafficking regulates the activity of the human dopamine transporter. J Neurosci. 19:1999;7699-7710. Cell fractionation and biotinylation techniques are used to establish the pathway for steady-state as well as PKC-mediated DAT endocytosis in transfected PC-12 cells. DAT is shown to be trafficked along with transferrin receptors through recycling endosomes, suggesting that PKC activation enhances internalization of DA transporters through a recycling pathway that is constitutively active in PC-12 cells.
14. Zhu S.J., Kavanaugh M.P., Sonders M.S., Amara S.G., Zahniser N.R. Activation of protein kinase C inhibits uptake, currents and binding associated with the human dopamine transporter expressed in Xenopus oocytes. J Pharmacol Exp Ther. 282:1997;1358-1365.
15. Daniels G.M., Amara S.G. Regulated trafficking of the human dopamine transporter. Clathrin-mediated internalization and lysosomal degradation in response to phorbol esters. J Biol Chem. 274:1999;35794-35801. The authors provide an analysis of phorbol ester-regulated DAT trafficking in live cells using a green fluorescent protein (GFP)-tagged DAT construct. PMA (phorbol ester)-induced, clathrin-mediated endocytosis of DAT relocates DATs to early endosomal compartments. Using protein-synthesis inhibition to diminish the synthesis and insertion of new transporters, Daniels and Amara show that DATs are degraded after internalization in this paradigm; this degradation is mediated by a lysosomal pathway.
16. Hoffman B.J., Hansson S.R., Mezey E., Palkovits M. Localization and dynamic regulation of biogenic amine transporters in the mammalian central nervous system. Front Neuroendocrinol. 19:1998;187-231.
17. ••)).
18. Benmansour S., Cecchi M., Morilak D.A., Gerhardt G.A., Javors M.A., Gould G.G., Frazer A. Effects of chronic antidepressant treatments on serotonin transporter function, density, and mRNA level. J Neurosci. 19:1999;10494-10501. This study provides evidence for the in vivo downregulation of SERT function following chronic SSRI treatments. Effects on SERTs are selective for the particular SSRI used. The fact that no change in transporter mRNA or serotonin levels was seen suggests that loss of antagonist binding sites may reflect an alteration in SERT protein abundance or trafficking.
19. Zhang L., Elmer L.W., Little K.Y. Expression and regulation of the human dopamine transporter in a neuronal cell line. Brain Res Mol Brain Res. 59:1998;66-73. Treatment of DAT-transfected Neuro-2A neuroblastomas with 1 μM cocaine for 24 h is reported to result in increased DAT-antagonist binding and DA uptake - these findings are not replicated in DAT-transfected COS-7 cells in the same study. These studies support an influence of ligand occupancy on biogenic amine transporter trafficking, but suggest that the ultimate effects on trafficking are dependent on the context of DAT expression, perhaps through the presence of different DAT-interacting proteins.
20. Apparsundaram S., Galli A., DeFelice L.J., Hartzell H.C., Blakely R.D. Acute regulation of norepinephrine transport: I. PKC-linked muscarinic receptors influence transport capacity and transporter density in SK-N-SH cells. J Pharmacol Exp Ther. 287:1998;733-743. This study provides evidence for G-protein-coupled receptor-mediated regulation of catecholamine transport in a noradrenergic neuroblastoma. Intracellular calcium- and PKC-linked pathways are implicated in M3 receptor actions on NETs. Changes in surface antagonist binding are consistent with receptor-modulated surface expression of NET proteins.
21. Dickinson S.D., Sabeti J., Larson G.A., Giardina K., Rubinstein M., Kelly M.A., Grandy D.K., Low M.J., Gerhardt G.A., Zahniser N.R. Dopamine D2 receptor-deficient mice exhibit decreased dopamine transporter function but no changes in dopamine release in dorsal striatum. J Neurochem. 72:1999;148-156. Evidence is provided for D2-receptor-mediated control of constitutive and regulated DAT expression. Analysis of D2 deficient mice reveals a loss of D2-receptor modulation of DATs in vivo. This study is the first to use receptor-deficient mice to demonstrate a role for a specific G-protein coupled receptor in transporter regulation.
22. Daws L.C., Gerhardt G.A., Frazer A.L. 5-HT1b antagonists modulate clearance of extracellular serotonin in rat hippocampus. Neurosci Lett. 266:1999;165-168. In vivo chronoamperometry techniques are used to show that 5-HT1b antagonists decrease the clearance rate for 5-HT in the CA3 region of rat hippocampus. This provides evidence that serotonin autoreceptors can regulate the activity of SERTs in vivo.
23. Beckman M.L., Bernstein E.M., Quick M.W. Multiple G protein-coupled receptors initiate protein kinase C redistribution of GABA transporters in hippocampal neurons. J Neurosci. 19:1999;RC9 (1-6). Activation of three different G-protein coupled receptors signaling through PKC activation is shown to reduce GABA uptake in cultured hippocamal neurons. Both kinetic analysis of transport and surface-biotinylation experiments show that the decrease in uptake corresponds to a shift in surface distribution of GAT1 from the plasma membrane to intracellular fractions. These findings reveal that GAT1 proteins, like SERT, NET and DAT proteins, are regulated through classical G-protein-coupled receptor signaling pathways.
24. max. J Neurochem. 68:1997;225-232.
25. Vaughan R.A., Huff R.A., Uhl G.R., Kuhar M.J. Protein kinase C-mediated phosphorylation and functional regulation of dopamine transporters in striatal synaptosomes. J Biol Chem. 272:1997;15541-15546.
26. Ramamoorthy S., Giovanetti E., Qian Y., Blakely R.D. Phosphorylation and regulation of antidepressant-sensitive serotonin transporters. J Biol Chem. 273:1998;2458-2466. The authors of this study use immunoprecipitation analyses in human hSERT stably-transfected HEK-293 cells to provide the first evidence for SERT phosphorylation by multiple kinases. The findings support the idea that multiple signaling pathways linked to the activation of protein kinases (PKC, PKA, PKG) and protein phosphatases (PP2A) support regulation of SERT expression. These findings and those of Huff and Vaughan (24,25), support a role for phosphorylation in the acute regulation of biogenic amine transporter expression.
27. Ramamoorthy S., Blakely R.D. Phosphorylation and sequestration of serotonin transporters differentially modulated by psychostimulants. Science. 285:1999;763-766. The authors demonstrate activity-dependent modulation of SERT phosphorylation and surface expression in stably transfected HEK-293 cells. The substrates 5-HT and amphetamine - but not antagonists such as antidepressants and cocaine - were able to block PKC-mediated increases in transporter phosphorylation as well as transporter sequestration. The authors propose a pathway by which ligands can sustain or prevent PKC-dependent transporter modulation either through conformational stabilization of SERTs or through an influence on SERT-associated proteins.
28. ••), proposes a mechanism whereby extracellular neurotransmitter can influence clearance capacity in a receptor-independent manner.
29. Beckman M.L., Quick M.W. Neurotransmitter transporters: regulators of function and functional regulation. J Membr Biol. 164:1998;1-10.
30. Beckman M.L., Bernstein E.M., Quick M.W. Protein kinase C regulates the interaction between a GABA transporter and syntaxin 1A. J Neurosci. 18:1998;6103-6112. This study identifies a regulatable association between the SNARE protein syntaxin 1A and the GABA transporter GAT1. Using endogenous and transfected models, they show that SNARE-transporter interactions are influenced by PKC activation, suggesting that phorbol ester-induced transporter downregulation is a consequence of the availability of syntaxin for interacting with GAT-1.
31. Chang A.S., Starnes D.M., Chang S.M. Possible existence of quaternary structure in the high-affinity serotonin transport complex. Biochem Biophys Res Commun. 249:1998;416-421. Initial observations that truncation mutants of mouse mSERT coexpressed with wild-type exhibit a dominant-negative effect led this group to investigate the possibility of SERT oligomerization. Concatenates of mSERT cDNA reveal that productive transport is possible when dimeric and tetrameric, but not trimeric, constructs are formed (although trimeric constructs still bind cocaine analogs); this suggests that the protein may function as a dimer or tetramer. Though indirect, the studies lend support to the idea that a higher-order homomultimeric complex supports 5-HT transport.
32. Kilic F., Rudnick G. Oligomerization of the serotonin transporter and its functional consequences. Proc Natl Acad Sci USA. 2000;. in press. Co-immunoprecipitation studies of differentially tagged SERT proteins reveal direct evidence for multimer formation. Multimers are recovered from cell-surface fractions, as identified by cell-surface biotinylation. A dominant activity of subunits with accessible cysteines for methanethiosulfonate (MTS) inactivation is described; this is consistent with a tetrameric structure for SERT proteins.
33. Zerangue N., Schwappach B., Jan Y.N., Jan L.Y. A new ER trafficking signal regulates the subunit stoichiometry of plasma membrane K(ATP) channels. Neuron. 22:1999;537-548.
34. Kitayama S., Ikeda T., Mitsuhata C., Sato T., Morita K., Dohi T. Dominant negative isoform of rat norepinephrine transporter produced by alternative RNA splicing. J Biol Chem. 274:1999;10731-10736. Two isoforms of rat rNET are cloned from rat brain; these isoforms represent alternatively spliced gene products. rNETa corresponds to the original human hNET isolate and is a functional 12 TMD protein. rNETb contains a longer carboxyl terminus and has no transport activity in transfected cells. rNETb acts in a dominant-negative fashion when coexpressed with rNETa. Although a limit to the specificity of this dominant-negative effect was defined, as rNETa significantly reduces the activity of other members of the gene family, rNETa does not influence expression of glutamate transporters. These findings support the possibility of NET multimer formation and suggest that coexpression of splice variant cDNAs in vivo may be associated with complex functional properties.
35. Porzgen P., Bonisch H., Hammermann R., Bruss M. The human noradrenaline transporter gene contains multiple polyadenylation sites and two alternatively spliced C-terminal exons. Biochim Biophys Acta. 1398:1998;365-370. A carboxy-terminal splice variant of unknown function is identified in SK-N-SH cells. Exons supporting differential carboxy-terminal splicing are identified. These studies support the idea that the carboxyl terminus of the human NET protein may be alternatively spliced although with a somewhat different pattern than that observed in bovine and rat NETs.
36. 2+ modulation of proline transporters, and suggest that transport and substrate-gated currents can be regulated independently.
37. Ingram S.L., Amara S.G. Arachidonic acid stimulates a novel cocaine-sensitive cation conductance associated with the human dopamine transporter. J Neurosci. 20:2000;550-557. Arachidonic acid applied to Xenopus oocytes expressing human DAT induces a nonselective cation conductance yielding currents as much as 50 times greater than that seen in response to DA. Previously identified DAT currents do not appear to be amplified; rather, a novel conducting state seems to have been induced. Whether this behavior is exhibited by other amine transporters is unknown, but at minimum it defines a new paradigm for amplified analysis of DAT behavior. If these currents occur in vivo, they suggest an additional mode of arachidonic acid signaling that could be supported by DAT proteins. Because DA potentiates the current observed with arachionic acid, such a conducting state may provide for convergent presynaptic signaling mediated by DA release and arachidonate production.
38. Kantor L., Gnegy M.E. Protein kinase C inhibitors block amphetamine-mediated dopamine release in rat striatal slices. J Pharmacol Exp Ther. 284:1998;592-598. Amphetamine-stimulated DA release in rat striatum is found to be sensitive to the prior application of PKC antagonists. Three different PKC inhibitors completely blocked amphetamine-induced DA release mediated by DAT with only modest effects on DA influx. This study provides evidence that influx and efflux can be regulated separately and that regulation independent of transporter trafficking may be controlled by PKC-dependent phosphorylation.
39. ••), wherein tonic PKC activity in the rat nucleus accumbens is suggested to support amphetamine-induced DA efflux through DATs. PKC antagonists also attentuate the locomotor response to amphetamine.
40. Nirenberg M.J., Vaughan R.A., Uhl G.R., Kuhar M.J., Pickel V.M. The dopamine transporter is localized to dendritic and axonal plasma membranes of nigrostriatal dopaminergic neurons. J Neurosci. 16:1996;436-447.
41. Tao-Cheng J.H., Zhou F.C. Differential polarization of serotonin transporters in axons versus soma-dendrites: an immunogold electron microscopy study. Neuroscience. 94:1999;821-830. Using pre-embedding immunogold techniques, the authors describe the polarized expression of SERT protein distribution in serotonergic neurons. Immunoreactivity in the cell bodies and dendrites is cytoplasmic, whereas labeling in axons is membrane-associated. The extensive distribution of SERTs along axonal membranes supports a contribution of SERTs to 5-HT clearance beyond just the synaptic cleft.
42. Schroeter S., Apparsundaram S., Wiley R.G., Miner L.H., Sesack S.R., Blakely R.D. Immunolocalization of the cocaine- and antidepressant-sensitive l-norepinephrine transporter. J Comp Neurol. 420:2000;211-232. This study reports NET localization in the rat central and peripheral nervous systems, using light- and electron-microscopic immunocytochemical techniques. NET labeled neurons are seen in traditional noradrenergic neurons including the locus ceruleus. NET-positive fibers are found throughout the forebrain as well in peripherally innervated structures such as the vas deferens. Labeling in many axons appears puncate and colocalizes with dopamine beta hydroxylase, consistent with a role for NETs in clearing synaptic NE. NET-positive fibers are found near, but not colocalized with, phenylethanolamine-N-methyl transferase labeled fibers, suggesting that NETs may also play a role in clearance of released epinephrine. Significant intracellular NET expression is detected in the adrenal gland, in contrast to SERT expression in adrenal chromaffin cells, which is associated with the plasma membrane.
43. Schroeter S., Levey A.I., Blakely R.D. Polarized expression of the antidepressant-sensitive serotonin transporter in epinephrine-synthesizing chromaffin cells of the rat adrenal gland. Mol Cel Neurosci. 9:1997;170-184.
44. - coupled transporters. BGT-1, a transporter for betaine that polarizes to the basolateral domain in MDCK cells, is found to utilize carboxy-terminal sequences for basolateral stability rather than directed basolateral trafficking. The carboxyl terminus of BGT-1 is found to associate with LIN-7, a protein implicated in epithelial polarity from worms to mammals. The findings suggest that similar interactions may stabilize or recruit homologous transporters at membrane subdomains.
45. Lesch K-P., Bengel D., Heils A., Sabol S.Z., Greenberg B.D., Petri S., Benjamin J., Müller C.R., Hamer D.H., Murphy D.L. Association of anxiety-related traits with a polymorphism in the serotonin transporter gene regulatory region. Science. 274:1996;1527-1531.
46. Cook E.H. Jr., Courchesne R., Lord C., Cox N.J., Yan S., Lincoln A., Haas R., Courchesne E., Leventhal B.L. Evidence of linkage between the serotonin transporter and autistic disorder. Mol Psych. 2:1997;247-250.
47. Klauck S.M., Poustka F., Benner A., Lesch K.P., Poustka A. Serotonin transporter (5-HTT) gene variants associated with autism? Human Mol Genet. 6:1997;2233-2238.
48. Greenberg B.D., McMahon F.J., Murphy D.L. Serotonin transporter candidate gene studies in affective disorders and personality: promises and potential pitfalls. Mol Psych. 3:1998;186-189.
49. Little K.Y., McLaughlin D.P., Zhang L., Livermore C.S., Dalack G.W., McFinton P.R., DelProposto Z.S., Hill E., Cassin B.J., Watson S.J., Cook E.H. Cocaine, ethanol, and genotype effects on human midbrain serotonin transporter binding sites and mRNA levels. Am J Psych. 155:1998;207-213. Radioligand binding to SERT proteins in postmortem brain sections reveal a reduced density of SERTs in cocaine users. SERT mRNA expression and transporter density are found to be influenced by SERT promotor polymorphisms. However, SERT binding was elevated in those ethanol abusers bearing short promoter alleles. These findings are consistent with a role for SERT promoter polymorphisms in predicting the risk for substance abuse.
50. Cook E.H., Stein M.A., Krasowski M.D., Cox N.J., Olkon D.M., Kieffer J.E., Leventhal B.L. Association of attention-deficit disorder and the dopamine transporter gene. Am J Med Genet. 56:1995;993-998.
51. Daly G., Hawi Z., Fitzgerald M., Gill M. Mapping susceptibility loci in attention deficit hyperactivity disorder: preferential transmission of parental alleles at DAT1, DBH and DRD5 to affected children. Mol Psych. 4:1999;192-196. This study reports preferential transmission of DAT alleles in ADHD, with the strongest findings reported in familial cases. The polymorphism tracked is not a coding mutation but may be linked with as yet unidentified coding alterations or noncoding mutations affecting DAT gene expression or, alternatively, affecting functional variants in a nearby gene.
52. Gainetdinov R.R., Wetsel W.C., Jones S.R., Levin E.D., Jaber M., Caron M.G. Role of serotonin in the paradoxical calming effect of psychostimulants on hyperactivity. Science. 283:1999;397-401. Studies of DAT-deficient mice that are spontaneously hyperactive reveal a paradoxical calming effect of the psychostimulant methylphenidate (Ritalin), a pharmacologic phenotype that is observed in subjects with ADHD. Although methylphenidate is only a weak hSERT antagonist, in vivo studies in DAT-deficient mice support a role for serotonergic modulation in the compound's calming actions. Cognitive impairments are also noted in DAT-deficient mice, although whether methylphenidate influences this phenotype is not reported. These studies encourage further exploration of DAT polymorphisms in human ADHD.
53. Shannon J.R., Flattem N.L., Jordan J., Jacob G., Black B.K., Biaggioni I., Blakely R.D., Robertson D. Orthostatic intolerance and tachycardia associated with norepinephrine-transporter deficiency. New Engl J Med. 342:2000;541-549. This is the first report of coding variants in a biogenic amine transporter associated with a physiologic disturbance. Subjects are identified as heterozygous for a single nucleotide polymorphism (SNP) that results in the switch of a highly conserved TMD9 alanine residue to proline. The mutant NET is shown to be nonfunctional in heterologous expression systems. Phenotypes of elevated plasma NE, reduced DHPG (dihydroxyphenylglycol) production and tachycardia on standing are found to segregate with the A457P allele.
54. - coupled neurotransmitter transporters.
55. •) focuses on blood pressure regulation and reveals multiple coding variants in the human NET gene. Although association studies remain to be conducted linking these coding variants to blood pressure, they augment significantly the number of known allelic variants of NETs and offer new opportunities to link transporter gene variation to cardiovascular traits.
56. Xu F., Gainetdinov R.R., Wetsel W.C., Jones S.R., Bohn L.M., Miller G.W., Wang Y.M., Caron M.G. Mice lacking the norepinephrine transporter are supersensitive to psychostimulants. Nat Neurosci. 3:2000;465-471. Xu and coworkers show that NET knockout mice have a diminished clearance capacity for NE and exhibit compensatory changes in dopaminergic signalling. See Update for further details.