Adenosine A2A receptor-Dopamine D2 receptor and Dopamine D2 receptor-Sigma-1 receptor heteroreceptor complexes (A2AR-D2R and D2R-S1R heteromers)

The Adenosine A2A receptor-Dopamine D2 receptor (A2A-D2) and Dopamine D2 receptor-Sigma-1 receptor (D2-sigma-1) heteroreceptor complexes are high-order molecular assemblies primarily located in the striatum of the basal ganglia (Fuxe et al., 2010). These complexes represent a sophisticated level of neurobiological integration where the Adenosine A2A receptor, Dopamine D2 receptor, and Sigma-1 receptor interact physically to modulate dopaminergic neurotransmission (Navarro et al., 2013). In the A2A-D2 heteromer, adenosine acts as an endogenous modulator that reduces the affinity of the D2 receptor for dopamine through antagonistic allosteric interactions, a process heavily implicated in the motor deficits of Parkinson's disease (Borroto-Escuela et al., 2018). The Sigma-1 receptor acts as a molecular chaperone within these complexes, stabilizing the D2 receptor and modulating the functional output of the A2A-D2 interaction, particularly in response to psychostimulants (Navarro et al., 2010). These heteroreceptor complexes are considered high-value therapeutic targets because they allow for the selective modulation of striatal signaling pathways while potentially minimizing side effects associated with targeting individual receptors distributed throughout the body (Ferré et al., 2018). Pharmacological intervention targeting these complexes, such as with A2A antagonists like istradefylline or Sigma-1 ligands like pridopidine, offers novel strategies for treating neurodegenerative diseases, schizophrenia, and substance use disorders. The unique pharmacological profile of these heteromers, distinct from their constituent monomers, provides a platform for developing heteromer-selective drugs with improved efficacy and safety profiles.

Other names

A2A-D2 heteromerD2-S1R heteromerA2AR-D2R-S1R trimeric complexStriatal GPCR heteromersAdenosine A2A-Dopamine D2-Sigma-1 receptor complex

Antagonistic allosteric modulation of Dopamine D2 receptor signaling by Adenosine A2A receptors and chaperone-mediated stabilization and trafficking regulation by Sigma-1 receptors.