Summary
Protein S (PS), a co-factor of activated protein C, is a vitamin K-dependent anticoagulant
protein and is known to be produced extrahepatically. In the present study, the concentration
of PS mRNA was determined tissue by tissue in the mouse, and it was high in lung,
adrenal and heart as well as in liver. We further investigated the effects of lipopolysaccharide
(LPS), tumor necrosis factor-α (TNF-α), and interleukin-1 (IL-1) on the PS mRNA expression
in murine tissues in vivo. Although LPS and TNF-α significantly decreased the expression
level of PS mRNA in all tissues examined (e.g., lung, liver, heart, and kidney) and
the PS antigen level in plasma, the suppressive effect of IL-1 on PS gene expression
was limited to heart. More specifically, considerable amounts of PS mRNA and antigen
were expressed in a cultured mouse cardiomyocyte cell line, and again, treatment with
IL-1 decreased the PS expression in these cells. These observations raise a possibility
that the expression of cardiac PS may contribute to the regional anticoagulant potential
in heart, and suggest that the decreased PS expression by cytokines may result in
an increase in the systemic and/or regional prothrombotic potential under inflammatory
conditions.
Keywords
Anticoagulant - interleukin-1 - tumor necrosis factor-α - cardiomyocyte - gene regulation