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A Novel Interaction between Complement Inhibitor C4b-binding Protein and Plasminogen That Enhances Plasminogen
Vaibhav Agarwal1, Simone Talens1, Alexander M Grandits1
1From the Medical Protein Chemistry, Translational Medicine, Lund University, 20502 Malmö, Sweden.
The Journal of Biological Chemistry
|June 13, 2015
Summary
We discovered a new interaction between C4b-binding protein (C4BP) and plasminogen, key players in the complement and fibrinolytic systems. This interaction, particularly during inflammation, impacts tissue homeostasis.
Area of Science:
- Immunology
- Biochemistry
- Hemostasis
Background:
- The complement, coagulation, and fibrinolytic systems are vital for tissue homeostasis.
- Interactions between these systems are increasingly recognized.
- C4b-binding protein (C4BP) is a complement inhibitor, and plasminogen is central to fibrinolysis.
Purpose of the Study:
- To investigate a novel interaction between C4BP and plasminogen.
- To elucidate the molecular mechanisms and functional consequences of this interaction.
Main Methods:
- Biochemical assays to study protein binding.
- Analysis of C4BP variants and their interaction with plasminogen.
- Assessment of functional consequences on C4BP cofactor activity and plasminogen activation.
Main Results:
- A novel interaction between C4BP and plasminogen was identified.
- The interaction is mediated by the CCP 8 domain of C4BP and lysine-binding sites of plasminogen.
- C4BP enhances plasminogen activation by urokinase-type plasminogen activator.
- C4BP-plasminogen complexes are found in human serum and plasma, particularly during acute phase responses.
Conclusions:
- This study reveals a previously unknown cross-talk between the complement and fibrinolytic systems.
- The C4BP-plasminogen interaction influences fibrinolytic activity and may play a role in inflammatory processes and tissue repair.
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