BAD-Glucokinase Axis Regulates Platelet Activation and Thrombosis.

Abstract

Background: BAD (Bcl2-associated death promoter), a member of the Bcl2 proapoptotic family, promotes cell apoptosis by sequestering the prosurvival proteins Bcl-XL and Bcl2 from the proapoptotic proteins BAK and BAX in nucleated cells. BAD is also expressed in platelets, playing a role in regulating platelet lifespan, apoptosis, and clearance. However, whether BAD regulates platelet activation and arterial thrombosis remains unclear.

Methods: The role of BAD in platelet activation and arterial thrombosis was investigated using BAD-deficient mice (Bad^-/-), in vitro functional studies, and arterial thrombosis models. The regulatory effect of BAD on platelet energy metabolism was detected using a Seahorse Extracellular Flux Analyzer. The regulatory effect of BAD on glucokinase was investigated by coimmunoprecipitation and activity measurement. The glucokinase heterozygous knockout mice (Gck^+/-) and activator were used to study its role in platelet activation.

Results: BAD-deficient mice (Bad^-/-) and wild-type mice transfused with Bad^-/- platelets displayed prolonged tail bleeding and arterial occlusion times. Bad^-/- platelets exhibited decreased aggregation in response to stimulations by proteinase-activated receptor 4-activating peptide, thrombin, and U46619. Furthermore, BAD ablation suppressed platelet integrin α_IIbβ₃ activation, granule secretion, and clot retraction induced by these agonists. Mechanistically, BAD interacted with glucokinase, and BAD deficiency resulted in decreased platelet glucokinase activity, mitochondrial oxidative phosphorylation, and mitochondrial ATP production. The partial loss of glucokinase (Gck^+/-) phenocopied platelet function defects caused by BAD deficiency, and a glucokinase activator rescued the impaired mitochondrial ATP production and function of Bad^-/- platelets. Additionally, the glucokinase activator enhanced human platelet activation.

Conclusions: Our findings demonstrate the critical role of the BAD-glucokinase axis in platelet activation and thrombosis, suggesting a potential target for antithrombotic therapy.