Hageman factor, platelets and polyphosphates: early history and recent connection.

Area of Science:

• Biochemistry
• Hematology
• Molecular Biology

Background:

• Platelet activation and blood coagulation are critical for hemostasis, inflammation, and tissue repair.
• Factor XII (FXII), also known as Hageman factor, initiates the intrinsic pathway of coagulation.
• A platelet-derived factor that promotes FXII activation was identified decades ago but remained biochemically uncharacterized.

Observation:

• Inorganic polyphosphates (poly P), polymers of phosphate residues, are present in human platelet dense granules.
• Platelet activation leads to the secretion of poly P.
• Released poly P has been shown to activate FXII.

Findings:

• Inorganic polyphosphates (poly P) are identified as the long-sought platelet-derived activator of Factor XII (FXII).
• Poly P plays a significant role in regulating both blood coagulation and fibrinolysis.
• This finding links platelet function directly to the initiation of the coagulation cascade via FXII activation.

Implications:

• The identification of poly P as the platelet FXII activator provides a molecular basis for understanding hemostasis.
• Understanding poly P's role may lead to novel therapeutic targets for bleeding disorders and thrombotic diseases.
• Further research into poly P's interactions with coagulation factors can elucidate its broader roles in inflammation and tissue repair.