Differential expression of protease nexin-1 (PN-1) mRNA in mice fetal tissues during gestation

Protease nexin-1 (PN-1) inhibits the activity of several serine proteases, including thrombin,, urokinase (uPA)-type plasminogen activator and trypsin. We investigated the stage- and tissue-specific pattern of PN-1 mRNA expression during gestation and in adult Balb/c mice. PN-1 mRNA expression in the whole fetus was the highest in day 8 post coitum (p.c.) and slightly decreased until day 18 p.c. The level of PN-1 mRNA in the placenta was highest in day 8 p.c. during gestation. PN-1 mRNA in the brain was highest in day 400 mature adults. On the other hand, PN-1 expression in the liver was highest in day 15 fetuses and then dramatically decreased to mature adults. The level of PN-1 mRNA was highest in the brain among the adult tissues tested. And, we found the expression of PN-1 mRNA in the heart, kidney, liver, lung, spleen, stomach, testis and thymus. However, we could not detect the expression of PN-1 in muscle and ovary tissues of mature adults. These results suggest that PN-1 expression has a stage- and tissue-specific during gestation to adults.