Abstract
Farnesyl pyrophosphate (FPP) is an intermediate in cholesterol biosynthesis, and it has also been reported to activate platelet LPA (lysophosphatidic acid) receptors. The aim of this study was to investigate the role of extracellular FPP in platelet aggregation. Human platelets were studied with light transmission aggregometry, flow cytometry and [³&sup5;S]GTPγS binding assays. As shown previously, FPP could potentiate LPA-stimulated shape change. Surprisingly, FPP also acted as a selective insurmountable antagonist to ADP-induced platelet aggregation. FPP inhibited ADP-induced expression of P-selectin and the activated glycoprotein (Gp)IIb/IIIa receptor. FPP blocked ADP-induced inhibition of cAMP accumulation and [³&sup5;S]GTPγS binding in platelets. In Chinese hamster ovary cells expressing the P2Y&sub1;&sub2; receptor, FPP caused a rightward shift of the [³&sup5;S]GTPγS binding curve. In Sf9 insect cells expressing the human P2Y&sub1;&sub2; receptor, FPP showed a concentration-dependent, although incomplete inhibition of [³H]PSB-0413 binding. Docking of FPP in a P2Y&sub1;&sub2; receptor model revealed molecular similarities with ADP and a good fit into the binding pocket for ADP. In conclusion, FPP is an insurmountable antagonist of ADP-induced platelet aggregation mediated by the P2Y&sub1;&sub2; receptor. It could be an endogenous antithrombotic factor modulating the strong platelet aggregatory effects of ADP in a manner similar to the use of clopidogrel, prasugrel or ticagrelor in the treatment of ischaemic heart disease.