TY - JOUR T1 - D<sub>2</sub> Receptors Regulate Dopamine Transporter Function via an Extracellular Signal-Regulated Kinases 1 and 2-Dependent and Phosphoinositide 3 Kinase-Independent Mechanism JF - Molecular Pharmacology JO - Mol Pharmacol SP - 1222 LP - 1232 DO - 10.1124/mol.106.027763 VL - 71 IS - 5 AU - Elizabeth A. Bolan AU - Bronwyn Kivell AU - Vanaja Jaligam AU - Murat Oz AU - Lankupalle D. Jayanthi AU - Yang Han AU - Namita Sen AU - Eneki Urizar AU - Ivone Gomes AU - Lakshmi A. Devi AU - Sammanda Ramamoorthy AU - Jonathan A. Javitch AU - Agustin Zapata AU - Toni S. Shippenberg Y1 - 2007/05/01 UR - http://molpharm.aspetjournals.org/content/71/5/1222.abstract N2 - The dopamine transporter (DAT) terminates dopamine (DA) neurotransmission by reuptake of DA into presynaptic neurons. Regulation of DA uptake by D2 dopamine receptors (D2R) has been reported. The high affinity of DA and other DAT substrates for the D2R, 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+) with live cell imaging techniques to identify the role of two D2R-linked signaling pathways, extracellular signal-regulated kinases 1 and 2 (ERK1/2), and phosphoinositide 3 kinase (PI3K) in mediating D2R regulation of DAT. Addition of the D2/D3 receptor agonist quinpirole (0.1–10 μM) to human embryonic kidney cells coexpressing human DAT and D2 receptor (short splice variant, D2SR) induced a rapid, concentration-dependent and pertussis toxin-sensitive increase in ASP+ accumulation. The D2/D3 agonist (S)-(+)-(4aR, 10bR)-3,4,4a, 10b-tetrahydro-4-propyl-2H,5H-[1]benzopyrano-[4,3-b]-1,4-oxazin-9-ol hydrochloride (PD128907) also increased ASP+ accumulation. D2SR 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+ 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 D2R stimulation. These experiments demonstrate that D2SR 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 D2R. Together, these results suggest a novel mechanism by which D2SRautoreceptors may regulate DAT in the central nervous system. The American Society for Pharmacology and Experimental Therapeutics ER -