Regulation of pharmacology by hetero-oligomerization between A1 adenosine receptor and P2Y2 receptor

Adenosine and ATP/UTP are main components of the purinergic system that modulate cellular and tissue functions via specific adenosine and P2 receptors, respectively. Here, we explored the possibility that A1 adenosine receptor (A1R) and P2Y2 receptor (P2Y2R) form heterodimers with novel pharmacological properties. Coimmunoprecipitation showed these receptors directly associate in A1R/P2Y2R-cotransfected HEK293T cells. Agonist binding by the A1R was significantly inhibited by P2Y2R agonists only in membranes from cotransfected cells. The functional activity of A1R, as indicated by the Gi/o-mediated inhibition of adenylyl cyclase, in the cotransfected cells was attenuated by the simultaneous addition of A1R and P2Y2R agonists. The increase in intracellular Ca2+ levels induced by P2Y2R activation of Gq/11 was synergistically enhanced by the simultaneous addition of an A1R agonist in the coexpressing cells. These results suggest that oligomerization of A1R and P2Y2R generates a unique complex in which the simultaneous activation of the two receptors induces a structural alteration that interferes signaling via Gi/o but enhances signaling via Gq/11.