P2Y14 receptor activation of platelets induces Ca2+ mobilization and Rho-GTPase-dependent motility that requires an interaction with P2Y1 receptors.

Abstract

Background and purpose: Platelet function during inflammation is dependent on activation by endogenous nucleotides acting on purinergic receptors. The P2Y₁₄ receptor has been reported to be expressed on platelets and is involved in leukocyte recruitment during inflammation. However, a role for P2Y₁₄ receptors in platelet function has not yet been determined.

Experimental approach: Platelets obtained from healthy human volunteers were incubated with the P2Y₁₄ receptor agonist, UDP-Glucose (UDP-G), and PPTN, a selective P2Y₁₄ receptor antagonist. Platelet activation was quantified using Ca²⁺ mobilization, aggregation and chemotaxis assays. Cooperativity with P2Y₁ receptor activation was also assessed after stimulation with UDP-G in the presence of MRS2500, a selective P2Y₁ receptor antagonist.

Key results: Ca²⁺ mobilization occurred in platelets after incubation with UDP-G in a concentration-dependent manner, and this was suppressed in platelets treated with PPTN. Platelets did not aggregate, or bind to fibrinogen after incubation with UDP-G. However, platelet chemotaxis towards f-MLP was dependent on P2Y₁₄ receptor stimulation with UDP-G and this was reduced by Rho-GTPase inhibitors. Furthermore, UDP-G-induced Ca²⁺ mobilization and chemotaxis were also inhibited when platelets were pretreated with MRS2500. Conversely, ADP-induced Ca²⁺ mobilization, chemotaxis and aggregation were not affected by the incubation with PPTN.

Conclusion and implications: Platelets can be activated via P2Y₁₄ receptor stimulation to induce chemotaxis but not aggregation. Furthermore, this was dependent on concomitant activation of P2Y₁ receptor. Activation of P2Y₁₄ receptors on platelets may therefore be relevant during inflammation, but cooperation with P2Y₁ receptor activation is required.