Regulation of Dopamine D1 Receptor Trafficking and Desensitization by Oligomerization with Glutamate N-Methyl-D-aspartate Receptors

Abstract

Activation of dopamine D 1 receptors is critical for the generation of glutamate-induced long-term potentiation at corticostriatal synapses. In this study, we report that, in striatal neurons, D 1 receptors are co-localized with N-methyl-D-aspartate (NMDA) receptors in the postsynaptic density and that they co-immunoprecipitate with NMDA receptor subunits from postsynaptic density preparations. Using modified bioluminescence resonance energy transfer, we demonstrate that D 1 and NMDA receptor clustering reflects the existence of direct interactions. The tagged D 1 receptor and NR1 subunit cotransfected in COS-7 cells generated a significant bioluminescence resonance energy transfer signal that was insensitive to agonist stimulation and that did not change in the presence of the NR2B subunit, suggesting that the D 1 receptor constitutively and selectively interacts with the NR1 subunit of the NMDA channel. Oligomerization with the NR1 subunit substantially modified D 1 receptor trafficking. In individually transfected HEK293 cells, NR1 was localized in the endoplasmic reticulum, whereas the D 1 receptor was targeted to the plasma membrane. In cotransfected cells, both the D 1 receptor and NR1 subunit were retained in cytoplasmic compartments. In the presence of the NR2B subunit, the NR1-D 1 receptor complex was translocated to the plasma membrane. These data suggest that D 1 and NMDA receptors are assembled within intracellular compartments as constitutive heteromeric complexes that are delivered to functional sites. Coexpression with NR1 and NR2B subunits also abolished agonist-induced D 1 receptor cytoplasmic sequestration, indicating that oligomerization with the NMDA receptor could represent a novel regulatory mechanism modulating D 1 receptor desensitization and cellular trafficking. Dopaminergic fibers originating in the substantia nigra and cortical glutamatergic neurons extensively interact in the striatum to drive the physiological functions of this structure from motor planning to reward seeking and procedural learning (1, 2). The critical importance of dopamine in this system is such that the degeneration of nigral dopaminergic neurons leads to the motor and cognitive deficits of Parkinson's disease (3).At the cellular level, nigral and cortical fibers converge on the medium spiny projection neurons (4), where dopamine D 1 -and D 2 -like receptors are coexpressed to high degree with glutamate NMDA 1 and non-NMDA receptor channels (5-8). From a functional point of view, it is well established that dopamine modulates the firing pattern of these neurons. In particular, there is evidence that dopamine, while attenuating the responses mediated by non-NMDA receptors, potentiates those associated with activation of NMDA receptors (2). The D 1 receptor appears to be involved in these interactions. In fact, activation of D 1 receptors in medium spiny neurons enhances NMDA-induced whole cell currents (2, 9) and is a critical requirement for the formation of NMDA-mediated long-term potentiation at corticostriatal...

Dopaminergic signaling in dendritic spines

“…First, western blot studies consistently detecte a substantial amount of D1 and D2 receptors in purified PSD fractions [41][42][43]. Second, DA receptors interact and co-localize with a number of PSD proteins in dendritic spines (see Section 6 below).…”

“…Besides short peptide sequences involved in G protein and arrestin binding, the remaining portions of these intracellular domains are presumably free to interact with other proteins. Using approaches such as co-immunoprecipitation and the yeast two-hybrid system, an increasing number of DRIPs are being identified [41][42][43]53,[68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83]. The confirmed DRIPs and their suggested functions are summarized in Table 1.…”

“…When D1 and NR1 were coexpressed in individual cells in the absence of the NR2B subunit, both were retained in cytoplasmic compartments. However, in the presence of NR2B, the NR1-D1 receptor complex was translocated to the plasma membrane, suggesting that D1 and NMDARs were assembled within intracellular compartments as constitutive heteromeric complexes [41]. In both heterologous cells and cultured neurons, activation of NMDARs recruited D1 receptors to the plasma membrane via a soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-dependent mechanism, resulting in enhancement of D1-mediated cAMP accumulation [84].…”

Dendritic distributions of dopamine D1 receptors in the rat nucleus accumbens are synergistically affected by startle-evoking auditory stimulation and apomorphine

“…Important clues are provided by our study in the basolateral amygdala, where we show that application of dopamine significantly decreases glutamate NMDA receptor-mediated postsynaptic currents through postsynaptic mechanisms, which may include co-trafficking of D1R and NMDA receptor . This is suggested by known protein-protein interactions between the C-terminals of D1R and the NR1 subunit of NMDA receptor (Lee et al, 2002;Fiorentini et al, 2003;Pei et al, 2004;Pickel et al, 2006). Dopaminergic and glutamatergic terminals converge on the same dendritic spine in the Acb (Sesack and Pickel, 1990;Pinto et al, 2003), where NMDA receptor antagonists also disrupt sensorimotor gating (Mansbach and Geyer, 1989;Bakshi et al, 1999).…”

Heteromeric Dopamine Receptor Signaling Complexes: Emerging Neurobiology and Disease Relevance

“…Similarly, in striatal postsynaptic density (PSD) preparations the C-terminal tail of the D1R, but not the D5R, coimmunoprecipitated with the NR1 subunit of the NMDA receptor (Fiorentini et al, 2003). The formation of the D1-NR1 heteromer was shown to occur through a strong and stable arginine-phosphate electrostatic interaction Woods and Ferré, 2005) and reported to be enhanced by ligand occupancy of the NMDA/glutamatebinding site of the NMDA receptor, to slow down lateral diffusion, and stabilize D1R localization in the synapse (Scott et al, 2006).…”