Journal: Frontiers in Synaptic Neuroscience
Article Title: Structure-Activity Investigation of a G Protein-Biased Agonist Reveals Molecular Determinants for Biased Signaling of the D 2 Dopamine Receptor
doi: 10.3389/fnsyn.2018.00002
Figure Lengend Snippet: Investigation of D2R internalization in non-neuronal cell systems. (A) HEK293 cells were transiently transfected with D2R-Rluc8 and a modified GFP10, which together produce constitutive bystander BRET. On the day of assay, the cells were stimulated with either dopamine (DA) or MLS1547 for 30 min at 37°C before BRET measurement. The data are graphed as mean dose-response curves from three independent experiments. DA exhibited an logEC50 of −7.00 ± 0.36 (EC50, 0.1 μM) for BRET reduction/D2R internalization, while MLS1547 treatment failed to alter the BRET signal. (B) Maximum BRET signal obtained after treatment with vehicle (control, 0.81 ± 0.02), 10 μM DA (0.65 ± 0.02), or 30 μM MLS1547 (0.79 ± 0.03). All data are expressed as mean ± SEM of the BRET ratio from three independent experiments. * P < 0.05, unpaired Student's t -test compared to untreated controls. (C) HA-tagged D2R was transiently transfected into HEK293 cells and surface D2R was biotinylated as described in Methods. After washing, cells were treated with either vehicle (control), 10 μM quinpirole, or 10 μM MLS1547 or for 30 min at 37°C. Biotin was cleaved from D2R that remained on the cell surface, followed by cell lysis and isolation of biotinylated (internalized) D2R using avidin beads. Western blotting was used to detect D2R and also transferrin receptor (TfR) (as a gel loading control). A single experiment, representative of three, is shown (the original full blot is displayed in the ). (D) Densitometric analyses were performed and the data expressed as D2R/TfR ratios, relative to the untreated controls (1.0). Treatment values are provided as mean ± S.E.M: quinpirole = 2.8 ± 0.2 and MLS1547 = 1.5 ± 0.03. One-way ANOVA followed by Bonferroni's post-test was performed: * p < 0.05, and ** p < 0.01.
Article Snippet: MLS1547 was originally obtained from the NIH Molecular Libraries Screening Center Network Library and subsequently purchased from MolPort (Riga, Latvija) for follow-up triage studies.
Techniques: Transfection, Modification, Control, Lysis, Isolation, Avidin-Biotin Assay, Western Blot