Blood Coagulation |
1 Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA
2 Center for Neurodegenerative and Vascular Brain Disorders and Interdisciplinary Program in Dementia Research, University of Rochester Medical Center, Rochester, NY, USA
Correspondence: John H. Griffin, Ph.D., Department of Molecular and Experimental Medicine (MEM-180), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA. E-mail: jgriffin{at}scripps.edu
Background: The protein C pathway down-regulates thrombin generation and promotes cytoprotection during inflammation and stress. In preclinical studies using models of murine injury (e.g., sepsis and ischemic stroke), murine protein S may be required because of restrictive species specificity.
Design and Methods: We prepared and characterized recombinant murine protein S using novel coagulation assays, immunoassays, and cell proliferation assays.
Results: Purified murine protein S had good anticoagulant co-factor activity for murine activated protein C, but not for human activated protein C, in mouse or rat plasma. In human plasma, murine protein S was a poor co-factor for murine activated protein C and had no anticoagulant effect with human activated protein C, suggesting protein S species specificity for factor V in addition to activated protein C. We estimated that mouse plasma contains 22±1 µg/mL protein S and developed assays to measure activated protein C co-factor activity of the protein S in murine plasma. Activated protein C-independent anticoagulant activity of murine protein S was demonstrable and quantifiable in mouse plasma, and this activity was enhanced by exogenous murine protein S. Murine protein S promoted the proliferation of mouse and human smooth muscle cells. The potency of murine protein S was higher for mouse cells than for human cells and similarly, human protein S was more potent for human cells than for mouse cells.
Conclusions: The spectrum of bioactivities of recombinant murine protein S with mouse plasma and smooth muscle cells is similar to that of human protein S. However, in vitro and in vivo studies of the protein C pathway in murine disease models are more appropriately performed using murine protein S. This study extends previous observations regarding the remarkable species specificity of protein S to the mouse.
Key words: anticoagulant, mitogenic activities, murine protein S.