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Hyperantithrombotic, noncytoprotective Glu149Ala-activated protein C mutant
Laurent O Mosnier1, Antonella Zampolli, Edward J Kerschen
1Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
Blood
|February 27, 2009
Summary
Activated protein C (APC) has anticoagulant and cytoprotective effects. Its cytoprotective actions, not anticoagulant ones, are crucial for reducing mortality in sepsis, highlighting potential for safer therapeutic development.
Area of Science:
- Biochemistry
- Pharmacology
- Molecular Biology
Background:
- Activated protein C (APC) is a vital anticoagulant and cytoprotective agent used in severe sepsis treatment.
- APC's dual activities involve factor Va/VIIIa inactivation (anticoagulant) and endothelial/protease-activated receptor signaling (cytoprotective).
- Understanding the distinct roles of these activities is key to developing safer, more effective APC-based therapies.
Purpose of the Study:
- To investigate the specific contributions of APC's anticoagulant and cytoprotective activities to its mortality-reducing effects in sepsis models.
- To compare APC mutants with selectively altered activity profiles to elucidate structure-function relationships.
- To identify key residues and regions responsible for distinct APC functions.
Main Methods:
- Protein engineering of APC mutants with modified anticoagulant or cytoprotective activities.
- In vitro assays to assess anticoagulant and cytoprotective functions.
- In vivo studies using endotoxin-induced murine models to evaluate antithrombotic effects and mortality reduction.
Main Results:
- Glu149Ala-APC showed enhanced anticoagulant/antithrombotic activity but reduced cytoprotective effects and mortality reduction in endotoxemia.
- 5A-APC (protease domain mutant) lacked antithrombotic activity but retained potent endotoxin shock mortality reduction.
- Residue Glu149 and the light chain's C-terminal region are critical for multiple APC activities.
Conclusions:
- APC's cytoprotective, not anticoagulant, activities are essential for reducing endotoxin-induced mortality.
- Antithrombotic activity alone is insufficient for reducing mortality in this sepsis model.
- Protein engineering of APC offers a pathway to dissect mechanisms and develop improved therapeutics with reduced bleeding risks.
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