Disease relevance of Slc6a3

• Here, we demonstrate that DAT constitutively internalizes and recycles in rat pheochromocytoma (PC12) cells [1].
• DAT also can transport dopamine neurotoxins and has been implicated in the selective vulnerability of nigrostriatal dopaminergic neurons in major models of Parkinson's disease [2].
• MSG treatment (4mg/g of body weight, administered on postnatal days 1, 3, 5, and 7) resulted in a reduction of D1 and D2 receptor expression from 30 days of age and persisted to adulthood (120 days of age), while DA transporter expression was significantly reduced from 14 days of age to adulthood [3].
• Lordosis in response to solicitous males was observed in females after intercerebral ventricular administration of DAT antagonists WIN35,428 (80 ng) and cocaine (0.016-1.6 micrograms) [4].
• These results indicate that anoxia enhances DA release by a mechanism involving both the reversed DA transporter and endogenous glutamate [5].

Psychiatry related information on Slc6a3

• With limited models of bipolar disorder, the DAT KD mice might provide a vehicle to screen for new psychiatric therapies to treat mania and its related symptoms [6].
• Our present demonstration that these piperidine structures do, in fact, possess significant DAT activity, taken together with their reported lack of locomotor activity, provides a compelling argument for exploring this class of molecules further in animal behavioral experiments [7].
• Haloperidol administration, but not clozapine, increased stereotyped behavior (p<0.01) in association with a decrease in striatal DAT expression (p<0.05) [8].
• Our findings suggest that sigma2 receptors are coupled to the DAT via a Ca2+/calmodulin-dependent protein kinase II transduction system in PC12 cells, and that sigma2 receptor antagonists might be useful in the treatment of drug abuse by blocking elevation of DA levels via reversal of the DAT [9].
• Bupropion, an efficacious antidepressant and smoking cessation agent, inhibits dopamine and norepinephrine transporters (DAT and NET, respectively) [10].

High impact information on Slc6a3

• The DA transporter is a 619-amino acid protein with 12 hydrophobic putative membrane-spanning domains and homology to the norepinephrine and gamma-aminobutyric acid transporters [11].
• Here, whole-cell patch clamp and perforated-patch recordings show that substrates of the dopamine transporter (DAT), such as dopamine (DA) and amphetamine, increase the firing activity of rat DA neurons in culture [12].
• Thus, in addition to clearing extracellular DA, our results suggest that the currents associated with DAT modulate excitability and may regulate release of neurotransmitter from midbrain DA neurons [12].
• These results demonstrate that aspartate and serine residues lying within the first and seventh hydrophobic putative transmembrane regions are crucial for DAT function and provide identification of residues differentially important for cocaine binding and for dopamine uptake [13].
• In addition, for rats of the sham-lesioned and severely lesioned groups, immunoradiolabeling for TH, the dopamine transporter (DAT), and the vesicular monoamine transporter (VMAT2) at the striatal level was not significantly different between rats treated with levodopa or vehicle [14].

Chemical compound and disease context of Slc6a3

• Selective DAT expression by dopaminergic neurons has led to use of cocaine analog DAT radioligands to assess rates of progression of dopamine neuronal degeneration in Parkinson's disease [15].
• To characterize the membrane pathway by which the cocaine-sensitive dopamine transporter (DAT) modulates progesterone receptor activation, steroid-dependent behavior lordosis was used in estrogen-primed ovariectomized Sprague-Dawley rats with stereotaxic implanted third ventricle cannulas [4].
• Analogs 5-16, in which the benzene ring in the phenylpropyl side chain of the GBR molecule had been replaced with a thiophene, furan, or pyridine ring, exhibited high affinity and selectivity for the DAT vs serotonin transporter (SERT) and stimulated locomotor activity in rats in a manner similar to the parent compound 2 [16].
• Also in contrast to effects of multiple METH injections, 1) MDMA caused little or no decrease in binding of the DAT ligand WIN35428, and 2) neither prevention of hyperthermia nor prior depletion of DA prevented the MDMA-induced reduction in plasmalemmal DA transport [17].
• The fact that posttreatment of methylphenidate after a neurotoxic regimen of METH protects against resulting loss of DA parameters suggests that treatment with methylphenidate, or other DA transporter blockers, may be protective against degenerative disorders of DA pathways, such as Parkinson's disease [18].

Biological context of Slc6a3

• In contrast, phorbol ester-mediated PKC activation accelerated DAT endocytosis and attenuated transporter recycling in a manner sensitive to DAT expression levels [1].
• Live cell fluorescence microscopy and cell surface biotinylation were used to study the effects of systematic deletions and alanine substitutions in the carboxyl terminus on DAT localization [19].
• Treatment of rat striatal tissue with okadaic acid (OA), a broad-spectrum protein phosphatase inhibitor, produces apparent maximal increases in DAT phosphorylation, suggesting that dephosphorylation is a crucial regulator of the DAT phosphorylation state [20].
• This increase in protein binding also was accompanied by an increase in DAT mRNA levels in the ventral tegmental area [21].
• Quantitative analysis of the specific binding indicated that WKY rats exhibited significant differences in DAT binding sites in the cell body as well as mesolimbic areas in comparison to WIS and S-D rats [22].

Anatomical context of Slc6a3

• Kinetic analyses reveal robust constitutive DAT cycling to and from the plasma membrane, independent of transporter expression levels [1].
• In primary cultures of rat embryonic midbrain neurons, DAT G585A, K590A, and D600A mutants were restricted to the cell soma and did not traffic to the dendrites or axonal processes [19].
• The effect of these three mutations on ER export of DAT was demonstrated in porcine aortic endothelial cells and the immortalized neuronal cell line 1RB3AN27 [19].
• It was found that alanine substitutions of Lys-590 and Asp-600 significantly delayed the delivery of DAT to the plasma membrane because of retention of DAT in the endoplasmic reticulum (ER) [19].
• In mPFC, nucleus accumbens and striatum, total DAT immunoreactivity was not different between EC and IC groups [23].

Associations of Slc6a3 with chemical compounds

• The dopamine transporter (DAT) removes dopamine from the extracellular milieu and is potently inhibited by number of psychoactive drugs, including cocaine, amphetamines, and methylphenidate (Ritalin) [1].
• The plasma membrane dopamine transporter (DAT) has an essential role in terminating dopaminergic neurotransmission by reuptake of dopamine into the presynaptic neurons [19].
• Most surprising, mutation of Gly-585 to alanine completely blocked the exit of DAT from the ER and surface expression of the transporter [19].
• In vitro dephosphorylation assays showed substantial removal of (32)PO(4) from DATs by PP1 but not by protein phosphatase 2A, protein phosphatase 2B, or protein tyrosine phosphatase, and this effect was blocked by OA, verifying that the (32)PO(4) loss from DAT was due to dephosphorylation [20].
• Alanine substitutions for six proline residues located in or near DAT transmembrane domains increase apparent affinity and decrease V(max) values for dopamine efflux mediated by these mutant transporters [24].

Physical interactions of Slc6a3

• In the SN, treatment with TIQ alone did not change TH level although it enhanced DA content and decreased [(3)H]GBR 12,935 binding to DAT in the substantia nigra pars compacta (SNc) [25].

Regulatory relationships of Slc6a3

• Our findings suggest that TNF-alpha plays a neuroprotective role in METH-induced drug dependence and neurotoxicity by activating plasmalemmal and vesicular DA transporter as well as inhibiting METH-induced increase in extracellular DA levels [26].

Other interactions of Slc6a3

• In comparison with TH, the mean area density of DAT-labeled axons was low throughout the VP [27].
• The addition of mesencephalic membrane fragments and striatal culture-conditioned media along with the cytokine mixture induced the expression of morphologically mature TH-ir cells that were also immunoreactive for dopa-decarboxylase, the DA transporter, and DA itself [28].
• DAT mRNA is not abundant in the hypothalamus and the olfactory bulb at any stage of development [29].
• Zitter mutant rats exhibiting a heterogeneous loss of striatal DA innervation were examined for DA transporter (DAT) binding and DA D3 receptor number by autoradiography and compared with Sprague-Dawley rats [30].
• We confirmed this possibility by observing that both tryptophan hydroxylase (the synthesizing enzyme for serotonin) and the DA transporter, proteins particularly susceptible to oxidative modification, were rapidly (within 30 min), but reversibly (returned to control levels by 36 hr) inactivated by a single administration of METH [31].

Analytical, diagnostic and therapeutic context of Slc6a3

• Using biotinylation and immunoblotting techniques, the present study examined whether the brain region-specific decrease in DA transporter (DAT) function is the result of a reduction in DAT cell surface expression [23].
• To further investigate the cellular mechanisms of these alterations, the present study used quantitative autoradiography and in situ hybridization to assess dopamine membrane transporter (DAT) protein density and mRNA expression in restricted-fed and free-fed adult male rats [21].
• The immunolabeled cells were subsequently assayed for their ability to express catecholamine transporter mRNAs by in situ hybridization using either a rat DAT or NET cRNA probe [32].
• We have used electron microscopic immunocytochemistry with an N-terminal domain anti-peptide antibody to examine the subcellular distribution of DAT in the rat SN and dorsolateral striatum [2].
• Antibodies specific for the dopamine transporter (DAT) was developed and characterized by immunoblot analysis, immunoprecipitation, and immunocytochemistry, and used for immunolocalization of transporter protein in rat brain at the light microscopic level [33].

References