D sub(2) Receptors Regulate Dopamine Transporter Function via an Extracellular Signal-Regulated Kinases 1 and 2-Dependent and Phosphoinositide 3 Kinase-Independent Mechanism
The dopamine transporter (DAT) terminates dopamine (DA) neurotransmission by reuptake of DA into presynaptic neurons. Regulation of DA uptake by D sub(2) dopamine receptors (D sub(2)R) has been reported. The high affinity of DA and other DAT substrates for the D sub(2)R, however, has complicated inv...
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Published in | Molecular pharmacology Vol. 71; no. 5; pp. 1222 - 1232 |
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Main Authors | , , , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
01.05.2007
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Online Access | Get full text |
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Summary: | The dopamine transporter (DAT) terminates dopamine (DA) neurotransmission by reuptake of DA into presynaptic neurons. Regulation of DA uptake by D sub(2) dopamine receptors (D sub(2)R) has been reported. The high affinity of DA and other DAT substrates for the D sub(2)R, however, has complicated investigation of the intracellular mechanisms mediating this effect. The present studies used the fluorescent DAT substrate, 4-[4-(diethylamino)-styryl]-N-methylpyridinium iodide (ASP super(+)) with live cell imaging techniques to identify the role of two D sub(2)R-linked signaling pathways, extracellular signal-regulated kinases 1 and 2 (ERK1/2), and phosphoinositide 3 kinase (PI3K) in mediating D sub(2)R regulation of DAT. Addition of the D sub(2)/D sub(3) receptor agonist quinpirole (0.1-10 mu M) to human embryonic kidney cells coexpressing human DAT and D sub(2) receptor (short splice variant, D sub(2S)R) induced a rapid, concentration-dependent and pertussis toxin-sensitive increase in ASP super(+) accumulation. The D sub(2)/D sub(3) agonist (S)-(+)-(4aR, 10bR)-3,4,4a, 10b-tetrahydro-4-propyl-2H,5H-[1]benzopyrano-[4,3-b]-1,4-oxazin-9- o l hydrochloride (PD128907) also increased ASP super(+) accumulation. D sub(2S)R activation increased phosphorylation of ERK1/2 and Akt, a major target of PI3K. The mitogen-activated protein kinase kinase inhibitor 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one (PD98059) prevented the quinpirole-evoked increase in ASP super(+) accumulation, whereas inhibition of PI3K was without effect. Fluorescence flow cytometry and biotinylation studies revealed a rapid increase in DAT cell-surface expression in response to D sub(2)R stimulation. These experiments demonstrate that D sub(2S)R stimulation increases DAT cell surface expression and therefore enhances substrate clearance. Furthermore, they show that the increase in DAT function is ERK1/2-dependent but PI3K-independent. Our data also suggest the possibility of a direct physical interaction between DAT and D sub(2)R. Together, these results suggest a novel mechanism by which D sub(2S)Rautoreceptors may regulate DAT in the central nervous system. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 content type line 23 ObjectType-Feature-2 |
ISSN: | 0026-895X |