Dopamine D-1 And Corticotrophin-Releasing Hormone Type-2 Alpha Receptors Assemble Into Functionally Interacting Complexes In Living Cells

Background and PurposeDopamine and corticotrophin-releasing hormone (CRH; also known as corticotrophin-releasing factor) are key neurotransmitters in the interaction between stress and addiction. Repeated treatment with cocaine potentiates glutamatergic transmission in the rat basolateral amygdala/cortex pathway through a synergistic action of D-1-like dopamine receptors and CRH type-2 receptors (CRF2 receptors). We hypothesized that this observed synergism could be instrumented by heteromers containing the dopamine D-1 receptor and CRF2 receptor.Experimental ApproachD(1)/CRF2 receptor heteromerization was demonstrated in HEK293T cells using co-immunoprecipitation, BRET and FRET assays, and by using the heteromer mobilization strategy. The ability of D-1 receptors to signal through calcium, when singly expressed or co-expressed with CRF2 receptors, was evaluated by the calcium mobilization assay.Key ResultsD(1)/CRF2 receptor heteromers were observed in HEK293T cells. When singly expressed, D-1 receptors were mostly located at the cell surface whereas CRF2 receptors accumulated intracellularly. Interestingly, co-expression of both receptors promoted D-1 receptor intracellular and CRF2 receptor cell surface targeting. The heteromerization of D-1/CRF2 receptors maintained the signalling through cAMP of both receptors but switched D-1 receptor signalling properties, as the heteromeric D-1 receptor was able to mobilize intracellular calcium upon stimulation with a D-1 receptor agonist.Conclusions and ImplicationsD(1) and CRF2 receptors are capable of heterodimerization in living cells. D-1/CRF2 receptor heteromerization might account, at least in part, for the complex physiological interactions established between dopamine and CRH in normal and pathological conditions such as addiction, representing a new potential pharmacological target.