A novel mutation in the P2Y(12) receptor and a function- reducing polymorphism in protease-activated receptor 1 in a patient with chronic bleeding

作者：Patel Y M; Lordkipanidze M; Lowe G C; Nisar S P; Garner K; Stockley J; Daly M E; Mitchell M; Watson S P; Austin S K; Mundell S J^*

来源：Journal of Thrombosis and Haemostasis, 2014, 12(5): 716-725.

DOI：10.1111/jth.12539

• bleeding disorder due to P2RY(12) defect
• blood platelets
• P2Y(12) purinoceptor
• point mutation
• receptors
• G-protein-coupled

BackgroundThe study of patients with bleeding problems is a powerful approach in determining the function and regulation of important proteins in human platelets. We have identified a patient with a chronic bleeding disorder expressing a homozygous P2RY12 mutation, predicting an arginine to cysteine (R122C) substitution in the G-protein-coupled P2Y(12) receptor. This mutation is found within the DRY motif, which is a highly conserved region in G-protein-coupled receptors (GPCRs) that is speculated to play a critical role in regulating receptor conformational states.
ObjectivesTo determine the functional consequences of the R122C substitution for P2Y(12) function.
Patient/methodsWe performed a detailed phenotypic analysis of an index case and affected family members. An analysis of the variant R122C P2Y(12) stably expressed in cells was also performed.
ResultsADP-stimulated platelet aggregation was reduced as a result of a significant impairment of P2Y(12) activity in the patient and family members. Cell surface R122C P2Y(12) expression was reduced both in cell lines and in platelets; in cell lines, this was as a consequence of agonist-independent internalization followed by subsequent receptor trafficking to lysosomes. Strikingly, members of this family also showed reduced thrombin-induced platelet activation, owing to an intronic polymorphism in the F2R gene, which encodes protease-activated receptor1 (PAR-1), that has been shown to be associated with reduced PAR-1 receptor activity.
ConclusionsOur study is the first to demonstrate a patient with deficits in two stimulatory GPCR pathways that regulate platelet activity, further indicating that bleeding disorders constitute a complex trait.

• 出版日期2014-5