Proteome analysis of a plasma membrane-enriched fraction at the placental feto-maternal barrier.

PURPOSE

We want to identify proteins that are part of or associated with the plasma membrane of the human feto-maternal barrier, which is crucially important for nutrient, gas, and waste exchange between the mother and the fetus. All transfer processes occur through one specialized endothelial cell layer, the multinuclear syncytiotrophoblast (STB). Specifically, the apical plasma membrane of the STB interacts with the maternal blood and is the site of initial transport processes across the placenta.

EXPERIMENTAL DESIGN

We used a proteomic approach that employed the enrichment of apical STB membranes isolated from healthy placentae by ultracentrifugation and saccharose gradient centrifugation steps in combination with 1-D SDS-PAGE and ESI-MS analysis.

RESULTS

We identified 296 different proteins, 175 of which were integral and peripheral membrane proteins, partially containing 1-12 transmembrane domains or lipid anchors. One hundred and sixty-one proteins (54%) were allocated to the plasma membrane.

CONCLUSIONS AND CLINICAL RELEVANCE

A high number of transporters, receptors, and proteins involved in signal transduction processes and vesicular trafficking were identified for the first time at the feto-maternal barrier. Our results are valuable sources for further studies of the cell physiology of the healthy placenta at the time of birth or the pathophysiology of several pregnancy disorders.