P2Y Nucleotide Receptor and Thrombosis: Insight beyond Plavix

Abstract

The discovery of platelet P2Y12 receptor leads to a new anti-thrombotic drug Plavix; however little is known about non-platelet P2Y receptors in thrombosis. This study tested the hypothesis that endothelial P2Y receptor(s) induces tissue factor (TF) expression, the initiator of coagulation cascade. Simulation of human coronary artery endothelial cells (HCAEC) by UTP/ATP increased TF mRNA, protein and its cell surface activity. RT-PCR detected expression of P2Y2 and P2Y11 receptors in HCAEC. Consistent with this, TF upregulation was inhibited by suramin or by siRNA silencing of P2Y2 receptor, but not by NF-157, a P2Y11-selective antagonist, suggesting a role for P2Y2 receptor. In addition, P2Y2 receptor activated ERK1/2, JNK and p38 MAPK pathways, without affecting the NF-kB pathway. Furthermore, TF upregulation was suppressed by inhibition of p38, or JNK, but not ERK1/2. Interestingly, blockade of the PLC/Ca2+ pathway did not affect P2Y2 receptor activation of p38, JNK and TF induction. However, blockade of Src kinase reduced activation of p38 but not JNK, eliminating TF induction. In contrast, inhibition of Rho kinase reduced activation of JNK but not p38, attenuating TF expression. These findings demonstrate P2Y2 receptor mediates TF expression in HCAECs through new mechanisms involving Src/p38 and Rho/JNK pathways, highlighting non-platelet P2Y receptor may contribute to the initiation of thrombosis.