Functional proteomics: Examining the effects of hypoxia on the cytotrophoblast protein repertoire

The outcome of human pregnancy depends on the differentiation of cytotropho blasts, specialized placental cells that physically connect the embryo/fetu s to the mother. As cytotrophoblasts differentiate, they acquire tumor-like characteristics that enable them to invade the uterus. In a novel feedback loop, the increasingly higher levels of oxygen they encounter within the u terine wall influence their differentiation into vascular-like cells. Toget her, the invasive and cell surface properties of cytotrophoblasts enable th em to form vascular connections with uterine blood vessels that divert mate rnal blood flow to the placenta, a critical hurdle in pregnancy. It is ther efore important to understand how cytotrophoblasts respond to changes in ox ygen tension. Here we used a proteomics approach, two-dimensional polyacryl amide gel electrophoresis (2-D PAGE) combined with mass spectrometry, to ch aracterize the protein repertoire of first trimester human cytotrophoblasts that were maintained under standard tissue culture conditions (20% O-2). 2 -D PAGE showed a unique protein map as compared to placental fibroblasts an d human JEG-3 choriocarcinoma cells. Mass spectrometry allowed the identifi cation of 43 spots on the cytotrophoblast map. Enzymes involved in glycolys is and responses to oxidative stress, as well as the 14-3-3 signaling/adapt er proteins, were particularly abundant. Hypoxia in vitro (2% O-2) produced discrete changes in the expression of a subset of proteins in all the afor ementioned functional categories. Together, these data offer new informatio n about the early gestation cytotrophoblast protein repertoire and the gene ralized mechanisms the cells use to respond to changes in oxygen tension at the maternal-fetal interface.