Understanding how a highly prevalent GRK5 polymorphism affects platelets and enhances thrombotic risk.

Area of Science:

• Genetics
• Molecular Biology
• Cardiovascular Research

Background:

• Inherited genetic variants influencing platelet function are linked to thrombotic disorders.
• The clinical significance of a specific G protein-coupled-receptor kinase 5 (GRK5) variant (rs10886430) and its mechanism in thrombotic risk are underexplored.

Purpose of the Study:

• To investigate the mechanistic link between the common GRK5 A>G variant (rs10886430) and the increased risk of thrombotic disorders observed in individuals with the GG genotype.

Main Methods:

• Compared GRK5 protein levels and platelet function in individuals with GG and AA genotypes.
• Utilized GRK5-/- iPSC-derived megakaryocytes, Grk5-deficient murine platelets, and a GRK5 inhibitor.
• Assessed platelet responsiveness, PAR1 signaling and internalization, and thrombus formation in microfluidic and murine thrombosis models.

Main Results:

• GG individuals exhibited a 90% reduction in GRK5 protein levels in platelets.
• GG platelets showed enhanced responsiveness to thrombin and PAR1 agonists, linked to reduced PAR1 internalization and signaling.
• GRK5 deficiency led to increased platelet accumulation under venous shear and enhanced thrombus formation in vivo.

Conclusions:

• The prevalent GRK5 GG genotype confers increased thrombotic potential by impairing PAR1 desensitization.
• This study establishes a direct link between a human genetic variant, altered thrombin receptor signaling, and thrombotic disease risk.