Impaired Platelet Function in Sept8-Deficient Mice In Vitro

Area of Science:

• Hematology
• Cell Biology
• Cytoskeletal Proteins

Background:

• Septins (Septs) are cytoskeletal proteins with diverse cellular roles.
• SEPT4 and SEPT8 were previously found in human platelets, localized near α-granules and translocating to the surface upon activation.

Purpose of the Study:

• To investigate the role of Septin 8 (SEPT8) in platelet function.
• To determine the impact of SEPT8 deficiency on platelet activation, aggregation, and hemostatic processes.

Main Methods:

• Utilized Septin 8 (SEPT8)-deficient mouse platelets for in vitro functional assays.
• Assessed integrin α_IIbβ₃ activation, α-granule and δ-granule exocytosis, and platelet aggregation.
• Evaluated platelet adhesion, spreading, procoagulant activity, and thrombin generation.

Main Results:

• SEPT8-deficient platelets exhibited significant defects in integrin α_IIbβ₃ activation, α-granule exocytosis, and aggregation, particularly with glycoprotein VI stimulation.
• No significant differences were observed in δ-granule and lysosome exocytosis between Sept8-deficient and wild-type platelets.
• Reduced platelet adhesion, delayed spreading, diminished procoagulant activity, and decreased thrombin generation were noted in SEPT8-deficient platelets.

Conclusions:

• Septin 8 (SEPT8) is essential for proper integrin α_IIbβ₃ activation, α-granule release, and platelet aggregation.
• SEPT8 plays a significant role in platelet-dependent thrombin generation and overall hemostatic processes.
• SEPT8 acts as a key modulator of distinct platelet functions critical for primary and secondary hemostasis.