Mode and site of interaction of the novel antiplatelet drug ticagrelor at the recombinant human P2Y12 receptor (1057.11)

Abstract

Ticagrelor is a perorally available P2Y12 receptor antagonist used for the prevention of cardiovascular events. In the present study, we analyzed the mode of action of ticagrelor at the recombinant human P2Y12 receptor and mutant constructs stably expressed in CHO Flp‐In cells. ADP and its analogue 2‐methylthio‐ADP (2‐MeSADP) decreased forskolin‐induced cAMP‐accumulation in a concentration dependent manner with 2‐MeSADP being more potent than ADP. Ticagrelor (3 to 10 nM) itself did not change basal and forskolin‐induced cAMP‐levels. Addition of ticagrelor at increasing concentrations led to increasing rightward shifts of the concentration‐response curves of ADP and 2‐MeSADP. An analysis according to Schild revealed pA2‐values of 8.7 with slopes of the linear regression lines not different from unity. These data are in agreement with a competitive mode of antagonism of ticagrelor against both agonists. The antagonistic potency of ticagrelor was maintained in cells expressing S101A‐, K173A/K174A‐, C248A‐, R256A‐ and K280A‐mutant constructs. In contrast, there were no rightward shifts of the concentration‐response curves of 2‐MeSADP and ADP by ticagrelor in cells expressing the C194A‐mutant P2Y12 receptor construct. Interestingly, antagonistic potencies of reactive blue 2 and analogues including PSB‐0739 (1‐amino‐4‐[4‐phenylamino‐3‐sulfophenylamino]‐9,10‐dioxo‐9,10‐dihydroanthracene‐2‐sulfonate) were increased in cells expressing the C194A‐mutant construct. In summary, our results suggest a competitive mode of antagonism of ticagrelor at the human P2Y12 receptor. The residue Cys194 (located in transmembrane region 5) appears to belong to the binding site of ticagrelor within the P2Y12 receptor protein. Grant Funding Source: Supported by the University of Bonn