Physical interaction between dopamine receptor type-1 (D1R) and CaV2.2 channels increases CaV2.2 function

CHOU-FREED CAMBRIA; RODRÍGUEZ, SILVIA S.; RAINGO JESICA; MC CARTHY CLARA INES

Cordoba

Congreso; XXXIII reunión anual de la Sociedad Argentina de Investigación en Neurociencias; 2018

Sociedad Argentina de Investigación en Neurociencias

D1R co-localizes with voltage-gated calcium channel CaV2.2 in rat PFC neurons, and the sole expression of D1R increases CaV2.2 membrane expression in a heterologous expression system. It has been proposed that this effect of D1R on CaV2.2 distribution depends on a physical interaction between CaV2.2 channels and the loop-2 region of D1R, but the effect of this D1R-CaV2.2 complex on CaV2.2 function remains unclear. Here, we investigate how D1R expression impacts CaV2.2 function and whether the D1R-CaV2.2 complex plays a role. We recorded whole-cell calcium currents in transfected HEK293t cells and found that low D1R expression (D1R:CaV2.2 molar ratio of 0.1) increased both CaV2.2 current density (170% of control, P=0.0029) and the number of functional CaV2.2 channels in the membrane (257% of control, P=0.0216 as measured by ON gating currents). Next, we generated mammalian expression vectors containing the sequence for the loop-2 or loop-1 region of D1R, with an IRES-YFP tag to test for expression. Competitive expression of D1R loop-2 occluded the increase in CaV2.2 current caused by D1R expression, while competitive expression of D1R loop-1 did not, indicating that the gain in CaV2.2 function due to D1R expression relies on a physical interaction between D1R and CaV2.2. Thus, we demonstrate that the D1R-CaV2.2 complex impacts not only CaV2.2 distribution, but also CaV2.2 function. Future experiments in PFC neurons will illuminate the physiological impact of these results.