Expression levels and localization of pregnancy-associated plasma protein-A2 (PAPP-A2) in mouse placenta and embryo

Pregnancy-associated plasma protein-A2 (PAPP-A2) is a metalloproteinase that specifically cleaves insulin-like growth factor binding protein-5 (IGFBP-5), a major modulator of insulin-like growth factor (IGF) bioavailability. Among several murine tissues surveyed, PAPP-A2 is most highly expressed in the placenta, and is also present in pregnancy serum and embryo. In the placenta, PAPP-A2 is localized in the junctional zone, where its degradation of IGFBP-5 may lead to the release of IGFs and so promote the development of the fetal portion of the placenta into the uterine wall. These expression patterns suggest that PAPP-A2 may play important roles during murine pregnancy. Cloning of the gene to further investigate its biochemical actions and allelic variation was also attempted. This work offers insight into the potential importance of a poorly-understood protein which may play crucial roles during pregnancy and fetal development in both mice and humans.