A gain-of-function filamin A mutation in mouse platelets induces thrombus instability

Area of Science:

• Cardiovascular Biology
• Hematology
• Genetics

Background:

• Filaminopathies A are rare X-linked disorders caused by filamin A (FLNA) gene mutations.
• Patients often present with macrothrombocytopenia and defective platelets.
• A male patient with a C-terminal FLNa mutation showed enhanced platelet functions, suggesting thrombosis risk.

Purpose of the Study:

• To investigate the in vivo thrombotic potential of a specific FLNa mutation identified in a male patient.

Main Methods:

• Established a mutant FlnA knock-in mouse model to mimic the patient's condition.
• Analyzed platelet function, bleeding time, and thrombosis in vivo.

Main Results:

• Mutant FlnA mouse platelets exhibited enhanced aggregation, secretion, and activation, mirroring patient findings.
• Mice showed normal bleeding time but increased re-bleeding, indicating hemostatic plug instability.
• In vivo thrombosis models revealed increased arteriolar emboli, confirming thrombus instability.

Conclusions:

• The FLNa mutation induces platelet hyperfunction in vitro and thrombus instability in vivo.
• This suggests a complex role for FLNa in regulating thrombus formation and stability.