Transcriptional regulation in the placenta during normal and compromised fetal growth.

The placenta synthesizes a number of cytokines and growth factors that are involved in the establishment, maintenance or regulation of pregnancy. Included are interferons, placental lactogens, other members of the growth hormone/prolactin gene family, leptin, and an array of angiogenic growth factors. While their roles in pregnancy differ, in their absence pregnancy is either lost or compromised. Therefore an understanding of the cell-specific transcriptional regulation of these genes is imperative if we are ever to alter their expression to benefit pregnancy progression. Our understanding of transcriptional regulation in the placenta is still in its infancy, and there appears to be considerable divergence in the transcriptional regulation of these genes between species, as well as between the various cytokine genes being examined. For example, while there are some commonalities in the regulation of human, rodent and ruminant placental lactogens, there are differences that require the study of placental lactogen gene regulation across species. However, one common theme that is emerging with the angiogenic growth factors, such as vascular endothelial growth factor and the angiopoietins, is the transcriptional control of these genes by oxygen tension within the placenta. Examination of transcriptional regulation in normal and compromised pregnancies will provide additional insight in this area.