Hexokinase controls platelet activation and hemostasis.

Area of Science:

• * Hematology
• * Biochemistry
• * Cell Biology

Background:

• * Platelet activation is energy-dependent, relying on glycolysis.
• * The specific roles of key glycolytic enzymes like hexokinases (HK) in platelet function are not fully understood.
• * Hexokinases (HK1 and HK2) are critical for glucose metabolism.

Purpose of the Study:

• * To investigate the roles of platelet hexokinases (HK1 and HK2) in regulating platelet bioenergetics, functions, and hemostasis.
• * To determine the impact of HK inhibition on thrombin- and convulxin-stimulated platelet responses.
• * To elucidate the distinct contributions of HK isoforms to specific platelet functions.

Main Methods:

• * Utilized pharmacological inhibitors: 2-deoxyglucose (2DG) for pan-HK inhibition and 3-bromopyruvate (3BP) for HK2-preferential inhibition.
• * Assessed platelet activation, glucose uptake, ATP production, glycolysis, aggregation, integrin activation, and α-granule secretion.
• * Evaluated in vitro thrombus formation and in vivo hemostasis in mice.

Main Results:

• * Platelet activation increased HK activity, with convulxin eliciting a stronger response than thrombin.
• * HK inhibition by 2DG and 3BP reduced activation-induced glucose uptake, ATP production, and glycolysis.
• * While platelet aggregation was reduced, it was not abolished, indicating metabolic flexibility.
• * Integrin activation and pro-coagulant platelet formation were suppressed by both inhibitors.
• * HK2 inhibition (3BP) selectively affected α-granule secretion, platelet spreading, and ROS generation.
• * Both inhibitors significantly reduced in vitro thrombus formation and increased bleeding time in mice.

Conclusions:

• * Hexokinases (HK1 and HK2) are central regulators of platelet metabolism and function.
• * Both HK isoforms are essential for activation-induced glucose metabolism and ATP production.
• * Distinct roles exist for HK isoforms in specific platelet responses like secretion and signaling.
• * HKs are critical for both in vitro and in vivo hemostasis, making them potential therapeutic targets.