S100A6 and its extracellular targets in Wharton's jelly of healthy and preeclamptic patients

• The level of the S100A6 protein in Wharton's jelly increases in preeclampsia.
• S100A6 binds to lumican and PRELP in Wharton's jelly.
• IGFBP-1 is a ligand of S100A6 only in preeclamptic Wharton's jelly.
• S100A6 competes with IGF-1 for binding to IGFBP-1.

IntroductionIn this work we compared the level, localization and binding partners of a calcium binding protein, S100A6, in extracellular matrix of Wharton's jelly of healthy and preeclamptic patients.MethodsStudies were performed on the umbilical cords taken from 10 newborns delivered by healthy and 10 newborns delivered by preeclamptic mothers. To characterize S100A6 in Wharton's jelly immunoblotting and immunohistochemistry were applied. For identification of S100A6 targets pull down assays and mass spectrometry were performed. Direct interaction of S100A6 with its targets was checked by ELISA while co-localization of these proteins was analyzed by immunofluorescence staining.ResultsWe have found that the level of S100A6 in Wharton's jelly is higher in patients with preeclampsia than in healthy ones and that post-translational modifications of S100A6 in preeclamptic tissue are different than those of S100A6 in control. We have identified several proteins that might interact with S100A6, among them are lumican and PRELP, found in Wharton's jelly of healthy and preeclamptic patients, and IGFBP-1 identified, as an S100A6 target, only in preeclamptic tissue. We have shown that the interactions between S100A6 and these proteins are direct and that IGF-1 competes with S100A6 for binding to IGFBP-1.ConclusionIn Wharton's jelly of preeclamptic tissue S100A6 is up-regulated and binds to different targets than in control. This suggests involvement of S100A6 in development of preeclampsia.