Heterogeneity of D2 dopamine receptors in different brain regions.
Ontology highlight
ABSTRACT:
SUBMITTER: Leonard MN
PROVIDER: S-EPMC1148583 | biostudies-other | 1987 Dec
REPOSITORIES: biostudies-other
Similar Datasets
Project description:Plasma membrane microcompartments could allow different signaling pathways to operate more efficiently and prevent cross-talk. We utilized a novel in-cell biotin transfer assay to demonstrate that the majority of plasma membrane-expressed D2 dopamine receptor (D2R) is microcompartmentalized within detergent-resistant structures. Conversely, a minority of D2R existed in a detergent-soluble form and interacted in a relatively unrestricted manner with other cellular proteins. The microcompartmentalization of D2R had functional consequences because dopamine-induced internalization of D2R was largely restricted to the compartmentalized receptor. The D2R-containing microcompartments did not correspond to putative detergent-resistant lipid raft structures. First, the detergent-insoluble D2R structures were significantly denser than detergent-resistant membrane fragments containing flotillin, a widely utilized lipid raft marker protein. Second, the detergent solubility of D2R was unaffected by treatment of cells with the cholesterol chelating agent, methyl-?-cyclodextrin, that is thought to disrupt lipid rafts. Finally, the in-cell biotinylation assay did not provide any evidence for the membrane compartmentalization of peptide motifs thought to target to lipid rafts. Thus, our observations form one of the first demonstrations, in living cells, of plasma membrane microcompartments defined by the ability of the compartment structure to broadly restrict the interaction of resident molecules with other cellular proteins.
| S-EPMC3642303 | biostudies-literature
Project description:Antisera have been raised against two peptides from the sequence of D2 dopamine receptors: peptide 1 from the predicted second extracellular loop and peptide 2 from the predicted third intracellular loop. The antisera recognize specifically a 95 kDa band in Western blots of several bovine brain regions, which corresponds to the denatured D2 dopamine receptor, whereas in recombinant CHO cells expressing D2 dopamine receptors a 80 kDa band is seen. The antisera immunoprecipitate 10-20% of the D2 dopamine receptors from soluble preparations of bovine brain. The antisera recognize D2 dopamine receptors in immunofluorescence analyses of recombinant CHO cells bearing the receptor gene. The antisera directed against the third intracellular loop, but not those against the second extracellular loop, will interfere with the coupling of D2 dopamine receptors and G-proteins in bovine brain preparations.
| S-EPMC1132245 | biostudies-other
Project description:MethodsSeven healthy volunteers underwent PET scans with [18F]altanserin and [11C]FLB 457 for 5-HT2A and D2 receptors, respectively. As a measure of receptor density, a binding potential (BP) was calculated from PET data for 76 cerebral cortical regions. A correlation matrix was calculated between the binding potentials of [18F]altanserin and [11C]FLB 457 for those regions. The regional relationships were investigated using a bicluster analysis of the correlation matrix with an iterative signature algorithm.ResultsWe identified two clusters of regions. The first cluster identified a distinct profile of correlation coefficients between 5-HT2A and D2 receptors, with the former in regions related to sensorimotor integration (supplementary motor area, superior parietal gyrus, and paracentral lobule) and the latter in most cortical regions. The second cluster identified another distinct profile of correlation coefficients between 5-HT2A receptors in the bilateral hippocampi and D2 receptors in most cortical regions.ConclusionsThe observation of two distinct clusters in the correlation matrix suggests regional interactions between 5-HT2A and D2 receptors in sensorimotor integration and hippocampal function. A bicluster analysis of the correlation matrix of these neuroreceptors may be beneficial in understanding molecular networks in the human brain.
| S-EPMC5722317 | biostudies-literature
Project description:Three-dimensional computer models of the rat D2, D3 and D4 dopamine receptor subtypes have been constructed based on the diffraction co-ordinates for bacteriorhodopsin, another membrane-bound protein containing seven transmembrane domains presumed to be arranged in a similar spatial orientation. Models were assembled by aligning the putative transmembrane domains of the dopamine receptors with those of bacteriorhodopsin using sequence similarities, and then superimposing these modelled alpha-helices on to the bacteriorhodopsin-derived co-ordinates. These models explore the potential hydrogen bonding, electrostatic and stacking interactions within the receptor which may be important for maintaining the conformation of these receptors, and thereby provide target sites for agonist binding. Proposed interactions between the catecholamine ligands and these receptors appear to account for the affinity, although not the specificity, of these agonist ligands for the different dopamine receptor subtypes. Such models will be useful for establishing structure-function relationships between ligands and the dopamine receptors, and may ultimately provide a template for the design of receptor-specific drugs.
| S-EPMC1133155 | biostudies-other
Project description:Influential neurocomputational models emphasize dopamine (DA) as an electrophysiological and neurochemical correlate of reinforcement learning. However, evidence of a specific causal role of DA receptors in learning has been less forthcoming, especially in humans. Here we combine, in a between-subjects design, administration of a high dose of the selective DA D2/3-receptor antagonist sulpiride with genetic analysis of the DA D2 receptor in a behavioral study of reinforcement learning in a sample of 78 healthy male volunteers. In contrast to predictions of prevailing models emphasizing DA's pivotal role in learning via prediction errors, we found that sulpiride did not disrupt learning, but rather induced profound impairments in choice performance. The disruption was selective for stimuli indicating reward, whereas loss avoidance performance was unaffected. Effects were driven by volunteers with higher serum levels of the drug, and in those with genetically determined lower density of striatal DA D2 receptors. This is the clearest demonstration to date for a causal modulatory role of the DA D2 receptor in choice performance that might be distinct from learning. Our findings challenge current reward prediction error models of reinforcement learning, and suggest that classical animal models emphasizing a role of postsynaptic DA D2 receptors in motivational aspects of reinforcement learning may apply to humans as well.
| S-EPMC4138746 | biostudies-literature
Project description:The Ca(2+)-binding protein calmodulin (CaM) has been shown to bind directly to cytoplasmic domains of some G protein-coupled receptors, including the dopamine D(2) receptor. CaM binds to the N-terminal portion of the long third intracellular loop of the D(2) receptor, within an Arg-rich epitope that is also involved in the binding to G(i/o) proteins and to the adenosine A(2A) receptor, with the formation of A(2A)-D(2) receptor heteromers. In the present work, by using proteomics and bioluminescence resonance energy transfer (BRET) techniques, we provide evidence for the binding of CaM to the A(2A) receptor. By using BRET and sequential resonance energy transfer techniques, evidence was obtained for CaM-A(2A)-D(2) receptor oligomerization. BRET competition experiments indicated that, in the A(2A)-D(2) receptor heteromer, CaM binds preferentially to a proximal C terminus epitope of the A(2A) receptor. Furthermore, Ca(2+) was found to induce conformational changes in the CaM-A(2A)-D(2) receptor oligomer and to selectively modulate A(2A) and D(2) receptor-mediated MAPK signaling in the A(2A)-D(2) receptor heteromer. These results may have implications for basal ganglia disorders, since A(2A)-D(2) receptor heteromers are being considered as a target for anti-parkinsonian agents.
| S-EPMC2788857 | biostudies-literature
Project description:By analyzing and simulating inactive conformations of the highly homologous dopamine D2 and D3 receptors (D2R and D3R), we find that eticlopride binds D2R in a pose very similar to that in the D3R/eticlopride structure but incompatible with the D2R/risperidone structure. In addition, risperidone occupies a sub-pocket near the Na+ binding site, whereas eticlopride does not. Based on these findings and our experimental results, we propose that the divergent receptor conformations stabilized by Na+-sensitive eticlopride and Na+-insensitive risperidone correspond to different degrees of inverse agonism. Moreover, our simulations reveal that the extracellular loops are highly dynamic, with spontaneous transitions of extracellular loop 2 from the helical conformation in the D2R/risperidone structure to an extended conformation similar to that in the D3R/eticlopride structure. Our results reveal previously unappreciated diversity and dynamics in the inactive conformations of D2R. These findings are critical for rational drug discovery, as limiting a virtual screen to a single conformation will miss relevant ligands.
| S-EPMC7053997 | biostudies-literature
Project description:D2 dopamine receptors from bovine brain (caudate nucleus and olfactory tubercle) have been solubilized using sodium cholate/NaCl and their glycoprotein properties studied in terms of their interaction with wheat-germ agglutinin-agarose (WGA-agarose). Under optimal conditions about 65% of the applied D2 dopamine receptors bound to WGA-agarose and could be eluted with N-acetylglucosamine. The ability of receptors to adsorb to the affinity column was shown to be dependent on the cholate and salt concentrations used. Digestion of the membrane bound D2 dopamine receptors with neuraminidase prior to solubilisation reduced the ability of the receptors to bind to WGA-agarose (50% of applied receptors bound) whereas digestion with N-acetylglucosaminidase did not significantly affect binding to WGA-agarose. Digestion with the two enzymes together resulted in a larger decrease in binding to WGA-agarose than was seen with the two enzymes alone (40% of applied receptors bound). Stepwise elution of bound receptors from the WGA-agarose columns using 2.5 mM- and 100-mM-N-acetylglucosamine showed that about 40% of the bound receptors interacted with WGA-agarose in a low-affinity manner, the remainder showing a high-affinity interaction. Neuraminidase treatment reduced the low-affinity population suggesting that the interaction of oligosaccharides bearing sialic acid with WGA-agarose is of lower affinity and that higher-affinity binding is via N-acetylglucosamine. These data are discussed in terms of the heterogeneity of carbohydrate moieties on the D2 dopamine receptors within a brain region. In all the tests applied here, however, receptors from caudate nucleus and olfactory tubercle behaved identically so their glycosylation patterns must be very similar.
| S-EPMC1135323 | biostudies-other
Project description:Dopamine D2 receptors (D2R) are G protein-coupled receptors that modulate synaptic transmission and are important for various brain functions, including learning and working memory. Abnormal D2R signaling has been implicated in psychiatric disorders such as schizophrenia. Here we report a new function of D2R in dendritic spine morphogenesis. Activation of D2R reduced spine number via GluN2B- and cAMP-dependent mechanisms in mice. Notably, this regulation occurred only during adolescence. During this period, D2R overactivation caused by mutations in the schizophrenia risk gene Dtnbp1 led to spine deficiency, dysconnectivity in the entorhinal-hippocampal circuit and impairment of spatial working memory. Notably, these defects could be ameliorated by D2R blockers administered during adolescence. Our findings suggest an age-dependent function of D2R in spine development, provide evidence that D2R dysfunction during adolescence impairs neuronal circuits and working memory, and indicate that adolescent interventions to prevent aberrant D2R activity protect against cognitive impairment.
| S-EPMC3832846 | biostudies-literature
Project description:The dopamine D(2) receptor (D2R) plays a critical role in diverse neurophysiological functions. D2R knock-out mice (D2R(-/-)) show reduced food intake and body weight while displaying an increased basal energy expenditure level, compared with their wild type littermates. Thus, these mice show a lean phenotype. D2R(-/-) mice displayed increased leptin sensitivity, and leptin injection induced increased phosphorylation of the hypothalamic signal transducer and activator of transcription 3 (STAT3) in D2R(-/-) mice relative to wild type littermates. Using double immunofluorescence histochemistry, we have demonstrated that D2Rs are present in leptin-sensitive STAT3-positive cells in the arcuate nucleus of the hypothalamus and that leptin injection induces STAT3 phosphorylation in hypothalamic neurons expressing D2Rs. Stimulation of D2R by the D2R agonist quinpirole suppressed the leptin-induced STAT3 phosphorylation and nuclear trans-localization of phospho-STAT3 in the hypothalamus of wild type mice. However, this regulation was not detected in the D2R(-/-) mice. Treatment of D2R agonist and antagonist could modulate the leptin-induced food intake and body weight changes in wild type mice but not in D2R(-/-) mice. Together, our findings suggest that the interaction between the dopaminergic system and leptin signaling in hypothalamus is important in control of energy homeostasis.
| S-EPMC2838312 | biostudies-literature