The expression of Argonaute2 and related microRNA biogenesis proteins in normal and hypoxic trophoblasts

Endogenous microRNAs (miRNAs) post-transcriptionally regulate mRNA and protein expression during tissue development and function. Whereas adaptation to environmental insults are tightly regulated in human tissues, the role of miRNAs and miRNA biogenesis proteins in this context is inadequately explored. We sought to analyse the expression of the key RNAi enzyme Argonaute2 (Ago2) and other miRNA biogenesis proteins in human trophoblasts during differentiation and in hypoxic environment. Using an in vitro analysis of primary term human trophoblasts, we identified the expression of the core miRNA biogenesis proteins in human villous trophoblasts, with expression levels unaffected by cellular differentiation. We found that the miRNA biosynthetic pathway was functional and produced miRNAs, with miR-93 up-regulated and miR-424 down-regulated in hypoxic environment. In contrast, hypoxia did not alter the expression of key miRNA machinery proteins. The pivotal miRNA processing enzyme Ago2, along with its interacting protein DP103, were expressed in normal placentas as well as in placentas from pregnancies complicated by placental hypoperfusion that resulted in fetal growth restriction. Ago2 and DP103 co-immunoprecipitated, and did not limit trophoblast response to hypoxic stress. We concluded that the core miRNA machinery proteins are expressed and functional in human trophoblasts. The influence of hypoxia on the expression of a subset of placental miRNA species is unlikely to reflect altered expression of key miRNA biogenesis proteins

Plasma hemopexin activity in pregnancy and preeclampsia

Objective: Plasma hemopexin activity, associated with increased vascular permeability, was evaluated in healthy pregnant and non-pregnant women and in pre-eclamptic women. Methods: Hemopexin activity and the hemopexin inhibitor, extracellular ATP, were assayed in plasma from pregnant (n=10), preeclamptic (n=9), and non-pregnant women (n=10) using standard methods. Abdominal fascia tissue fragments from preeclamptic and pregnant women were immunohistochemically stained for vascular ectoapyrase or ecto-5'nucleotidase. Results: The data show significantly enhanced Hx activity exclusively in plasma from pregnant women and significantly enhanced plasma ATP in pre-eclamptic women compared with the other groups. Dephosphorylation of preeclamptic plasma resulted in reactivation of Hx activity. Fascia tissue-samples from preeclamptic women showed reduced ecto-apyrase activity and enhanced ecto-5'nucleotidase activity compared to pregnant women. Conclusion: Enhanced hemopexin activity may be associated with normal pregnancy, but not with preeclampsia. Decreased hemopexin in pre-eclamptic patients may be due to enhanced plasma ATP, which is possibly promoted by diminished activity of vascular ecto-apyrase