Fibrinogen and fibrin structure and functions.

Area of Science:

• Biochemistry
• Molecular Biology
• Hematology

Background:

• Fibrinogen, a key protein in blood clotting, consists of Aalpha-, Bbeta-, and gamma-chains forming D and E domains.
• Fibrin formation, initiated by thrombin cleavage of fibrinopeptide A (FPA), involves polymerization and cross-linking by factor XIIIa.
• Fibrin(ogen) possesses multiple binding sites involved in diverse biological functions beyond clot structure.

Purpose of the Study:

• To review the detailed structure of fibrinogen and fibrin.
• To correlate fibrin(ogen) structure with its multifaceted biological functions.
• To elucidate the molecular mechanisms underlying fibrin's roles in hemostasis and other processes.

Main Methods:

• Literature review of fibrinogen and fibrin structure-function relationships.
• Analysis of molecular interactions and binding sites.
• Synthesis of information on fibrin's roles in clotting, cell interactions, and signaling.

Main Results:

• Fibrin assembly involves D:E associations and lateral fibril interactions, forming a clot network.
• Fibrin(ogen) modulates factor XIII activity, binds thrombin (antithrombin I), and enhances plasminogen activation by tPA.
• Fibrin(ogen) interacts with extracellular matrix proteins, growth factors, cytokines, platelets, and leukocytes, influencing angiogenesis and immune responses.

Conclusions:

• Fibrinogen and fibrin are structurally complex proteins with diverse biological roles extending beyond clot formation.
• Fibrin's interactions with various molecules and cells are crucial for hemostasis, thrombosis, and inflammatory processes.
• Understanding these interactions provides insights into potential therapeutic targets in cardiovascular and inflammatory diseases.