TNIK as a molecular switch regulating platelet function in hemostasis and hyperlipidemia-associated thrombosis

Area of Science:

• Hematology
• Molecular Biology
• Cardiovascular Research

Background:

• Platelets balance hemostasis and thrombosis, especially during metabolic stress.
• Mitogen-activated protein kinases (MAPKs) are key in platelet responses, but their specific roles are unclear.
• The function of Traf2/Nck-interacting kinase (TNIK) in platelet regulation needs investigation.

Purpose of the Study:

• To investigate the role of TNIK in platelet function, hemostasis, and thrombosis.
• To elucidate the distinct signaling pathways regulated by TNIK under normal and hyperlipidemic conditions.
• To determine if TNIK is a potential therapeutic target for metabolic thrombotic disorders.

Main Methods:

• Generated megakaryocyte/platelet-specific TNIK-knockout mice (Tnikf/f PF4-Cre+).
• Utilized chimeric Tnikf/f PF4-Cre+ Apoe-/- mice fed high-fat diets to model hyperlipidemia.
• Evaluated platelet function, hemostasis, and arterial thrombosis using various assays.

Main Results:

• TNIK deficiency prolonged bleeding and delayed thrombosis under normal conditions, linked to impaired dense granule secretion and MLK3/MKK4/JNK pathway activation.
• Under hyperlipidemic conditions, TNIK deficiency accelerated thrombosis and enhanced platelet response to oxidized LDL.
• TNIK suppressed the NOX2/ROS/ERK5 pathway via binding to PKCε, inhibiting excessive platelet activation in hyperlipidemia.

Conclusions:

• TNIK acts as a molecular switch in platelets, promoting hemostasis while preventing hyperlipidemia-associated thrombosis.
• Distinct signaling pathways mediate TNIK's dual role in platelet function.
• TNIK is a potential therapeutic target for metabolic thrombotic disorders.