| First Author | Paul DS | Year | 2023 |
| Journal | J Thromb Haemost | Volume | 21 |
| Issue | 7 | Pages | 1891-1902 |
| PubMed ID | 36958516 | Mgi Jnum | J:342773 |
| Mgi Id | MGI:7529318 | Doi | 10.1016/j.jtha.2023.03.013 |
| Citation | Paul DS, et al. (2023) Loss of P2Y(1) receptor desensitization does not impact hemostasis or thrombosis despite increased platelet reactivity in vitro. J Thromb Haemost 21(7):1891-1902 |
| abstractText | BACKGROUND: The hemostatic plug formation at sites of vascular injury is strongly dependent on rapid platelet activation and integrin-mediated adhesion and aggregation. However, to prevent thrombotic complications, platelet aggregate formation must be a self-limiting process. The second-wave mediator adenosine diphosphate (ADP) activates platelets via Gq-coupled P2Y(1) and Gi-coupled P2Y(12) receptors. After ADP exposure, the P2Y(1) receptor undergoes rapid phosphorylation-induced desensitization, a negative feedback mechanism believed to be critical for limiting thrombus growth. OBJECTIVE: The objective of this study was to examine the role of rapid P2Y(1) receptor desensitization on platelet function and thrombus formation in vivo. METHODS: We analyzed a novel knock-in mouse strain expressing a P2Y(1) receptor variant that cannot be phosphorylated beyond residue 340 (P2Y(1)(340-0P)), thereby preventing the desensitization of the receptor. RESULTS: P2Y(1)(340-0P) mice followed a Mendelian inheritance pattern, and peripheral platelet counts were comparable between P2Y(1)(340-0P/340-0P) and control mice. In vitro, P2Y(1)(340-0P/340-0P) platelets were hyperreactive to ADP, showed a robust activation response to the P2Y(1) receptor-selective agonist, MRS2365, and did not desensitize in response to repeated ADP challenge. We observed increased calcium mobilization, protein kinase C substrate phosphorylation, alpha granule release, activation of the small GTPase Rap1, and integrin inside-out activation/aggregation. This hyperreactivity, however, did not lead to increased platelet adhesion or excessive plug formation under physiological shear conditions. CONCLUSION: Our studies demonstrate that receptor phosphorylation at the C-terminus is critical for P2Y(1) receptor desensitization in platelets and that impaired desensitization leads to increased P2Y(1) receptor signaling in vitro. Surprisingly, desensitization of the P2Y(1) receptor is not required for limiting platelet adhesion/aggregation at sites of vascular injury, likely because ADP is degraded quickly or washed away in the bloodstream. |
